How Principals of Successful Schools Enact Education Policy: Perceptions and Accounts From Senior and Middle Leaders

ABSTRACT This article investigates, from the perspective of senior and middle leaders, how secondary principals in England lead their schools to achieve sustainable performance despite policy shifts. Empirical data were drawn from structural equation modeling (SEM) analyses of a questionnaire survey from 309 effective and improved secondary schools in England and longitudinal interview data from a subsample of four case-study schools. The research suggests that what the principals were perceived to be doing successfully was to use policies as opportunities—purposefully, progressively, and strategically—to regenerate coherent cultures and conditions which support the staff to learn to renew their practice.

Over the last 40 years, the research literature has consistently reported that principal leadership is instrumental in bringing about improved learning outcomes in schools (Barth, 1976;Day, Gu, & Sammons, 2016;Leithwood, Day, Sammons, Harris, & Hopkins, 2006;Robinson, Lloyd, & Rowe, 2008;Ni, Yan, & Pounder, 2018;Sammons, Gu, Day, & Ko, 2011;Silins & Mulford, 2002). The literature has also been in strong agreement that principals contribute to student learning largely indirectly through leadership activities and influence, particularly through building school capacity and (re)designing structural, sociocultural, and relational processes that are conducive to promoting professional learning communities and raising the quality of teaching and learning (Bryk, Sebring, Allensworth, Luppescu, & Easton, 2010;Day et al., 2011;Gu & Johansson, 2013;Hallinger & Heck, 2010a, 2010bLeithwood, Harris, & Strauss, 2010;Leithwood, Sun, & Pollock, 2017;Sun & Leithwood, 2012, 2015a. However, although the literature on successful principal leadership has become increasingly extensive over the last decade, knowledge about how key staff (i.e., senior and middle leaders in their schools) perceive the ways in which school principals make a difference to student outcomes tends to be limited. In particular, the literature has been relatively silent on how the key staff perceive the roles and practices of their principals in managing external policy demands and increased accountability pressures for sustained improvement over time.
In this article we investigate, from the perspective of senior and middle leaders, the ways in which some secondary principals in England had led their schools to achieve sustainable high performance in the face of intense reform efforts and policy shifts. As we have explained in the editorial of this special issue, the research upon which this article is based is not about policy or policy analysis, but about successful principal leadership in times of intensive and pervasive policy reforms. We will thus not engage with the political and sociological debates about the pedagogical challenges, professional tensions, and ethical dilemmas that education policies and reforms have produced for school leaders and teachers (e.g., Fuhrman, 1999;Mitchell, Crowson, & Shipps, 2011;Payne, 2008). Rather, we argue that the political, professional, and accountability pressures created by incoherent, disjointed, and at times contradictory external policy initiatives are part of the broad environments in which "schools and education policy subsist" (Cohen, Moffitt, & Goldin, 2007, p. 526) in many systems, including England, and within which schools in our research managed to continue to make a difference to students' academic performance. Put simply, policy shifts have become unavoidable political realities of education in many systems. However, whilst some schools not only survive but also continue to thrive in the face of challenging and changing environments, others struggle and falter.
This article focuses on findings from structural equation modeling (SEM) analyses of a questionnaire survey of 1,054 senior and middle leaders from 309 secondary schools that were identified as more successful from analyses of national performance data in England (improving in their academic effectiveness and receiving positive inspection results) and analyses of longitudinal interview data from a subsample of four case-study schools. Through the eyes and experiences of senior and middle leaders, this article, together with the rest of the articles in this special issue, aims to forge new, productive directions for research on policy enactment by linking it more closely with the literature on school leadership and, through this, exploring how principals of high-performing schools strategically and purposefully engage with external policy demands for coherent organizational change and sustained improvement.

Connecting leadership with policy enactment
Over the last 40 years, scholars have based their conceptualization of policy enactment and implementation on a range of critical sociological (Ball, 1994;Ball, Maguire, & Braun, 2012;Maguire, Braun, & Ball, 2015), organizational (Elmore, 1995;Hubbard, Mehan, & Stein, 2006;Manning, 1982;Newmann, 1996), social psychological (Weick, 1979(Weick, , 1995(Weick, , 2005, and cognitive theories (e.g., Spillane, Reiser, & Reimer, 2002;. The critical sociological approach to examining how schools enact policy conceptualizes policy as text (Ball, 1994) in that it is "complexly encoded in sets of texts and various documents and it is also decoded in complex ways" (Braun et al., 2011, p. 586). Such a conceptual lens has allowed for an understanding of policy enactment as a creative, sophisticated, and complex process (Braun, Maguire, & Ball, 2010) in which "policies are interpreted and 'translated' by diverse policy actors in the school environment" (Ball, 1994, p. 19). Ball et al. (2012) argue that the enactment of policies is "an iterative process of making institutional texts and putting those texts into action" (2012, p. 45), and that enactment of policies is "always more than just implementation" because "they bring together contextual, historic and psychosocial dynamics into a relation with texts and imperatives to produce action and activities that are policy" (2012, p. 71). In their seminal research on how four "ordinary" coeducational, nondenominational, and nonselective secondary schools enact policy, Ball and colleagues (2012) observed that At the center of policy enactment is the school-but the school is neither a simple nor a coherent entity, there is a need to understand schools as far more differentiated and loosely assembled than is often the case. Schools are not of a piece. They are precarious networks of different and overlapping groups of people, artefacts and practices. (2012, p. 144) Indeed, the narrative accounts of how teachers and other adults from the four case-study schools interpreted, translated, and implemented various external policies in their own contexts of work showed that these policy actors are not only producers and consumer of policy, but also readers and writers of policy . This evidence highlights the localized and situated nature of policy actions . It also reveals that enacting policies in schools is a process of recontextualization in which policy actors work creatively in diverse ways to "fabricate and forge practices out of policy texts and policy ideas in the light of their situated realities" (Ball et al., 2012, p. 142).
Although writing from different theoretical perspectives to understand and explain how people in organizations and schools make sense of policies and implement them, Weick (1995Weick ( , 2005 and Spillane (2004) have both emphasized the situated nature of sense making in the policy enactment process and the importance of considering how people make sense of their environments in this process. Thus, making sense of policies is not a passive process of decoding the information in the policy texts (Von Glasersfeld, 1989). Rather, in this process people as social agents "construct, rearrange, single out, demolish many objective features of their surroundings" (Weick, 1979, p. 164) and ultimately transform their environments . Using the sense-making frame to examine how school leaders enact district-level accountability policies, Spillane and his colleagues (2002) concluded that : Managing in the middle in an era of accountability can also have advantages. Skillful school leaders can use accountability policies to augment their authority with respect to instruction. . . . Hence, school leaders can interpret district accountability policies in ways that support their own reform agendas and use them to augment their influence over staff. Because the stakes are high, they can use district accountability measures to add considerable clout to their own efforts to transform practice in particular ways. (Spillane et al., 2002, p. 760) The conceptual and empirical connections that Spillane and his colleagues have established between school leadership and policy enactment are important because schools' responses to external policies are the result of the "function not only of leaders' identities but also the multiple contexts in which their sense-making is situated" (2002, p. 755). They remind us that in schools, enacting policies is an organizational behavior which is crafted and shaped by school leaders, and principals especially, who set the directions of the school and can act to redesign the organization. How these leaders interpret and make sense, rationally and emotionally, of what a particular policy means to their schools and then decide "whether and how to ignore, adapt, or adopt" this policy locally (Spillane et al, 2002, p. 733) influences not only how the policy is interpreted by their teachers and how effectively it is implemented in the school, but importantly, the extent to which the actions of "enactment" are likely to disrupt, constrain, or advance further improvement of the school. In this sense, enactment links closely with the principal's role in their diagnosis of the school's needs and challenges and the focus on particular priorities in consequence. As our empirical research in this article shows, principals who do well know how to use policies as opportunities to create organizational conditions and regenerate school capacities for enhanced progress and performance which are not restricted only to academic attainment results.
In their analysis of how schools strategically manage multiple external demands, Honig and Hatch (2004) found that although some researchers argue that multiple policy demands in such environments strain schools' "ability to operate in coordinated and productive ways," others maintain that they may "add up to important new opportunities for school improvement" (Honig & Hatch, 2004, p. 16). By conceptualizing policy coherence as a dynamic and ongoing process, as opposed to an objective reality, they argue that schools are a central agent in crafting coherence between external demands and internal goals and strategies. In his earlier work, Hatch (2002) emphasized that schools are part of an ecosystem in which "many different entities are trying to co-exist" and in which "changes are constantly underway" (Hatch, 2002, p. 632). Honig and Hatch argue that "multiple external demands do not present a problem to be solved but an ongoing challenge to be managed, a potential opportunity for schools to increase necessary resources, and an important arena of organizational activity" (2004, p. 26-7). By extension, we argue that to create and embed coherence between policy and practice within the particular context of a school's organization requires strong leadership. We ascribe to the view of the superintendent in Hubbard, Mehan and Stein's (2006) research on how schools learn from reforms that "coherence making at the end is what leadership is about" (2006, p. 157).

The research: Mixed-methods design
This article draws upon empirical evidence from a UK Economic and Social Research Council (ESRC) and Hong Kong Research Grants Council (RGC) funded two-year bilateral research project on how "successful" secondary schools in England and Hong Kong mediated government policies in furthering their own broad improvement agendas. The primary purpose of this research was to advance understandings of how mandated government reforms were mediated by principals, senior and middle leaders, and teachers in improved and effective schools which served communities of contrasting socioeconomic advantage. The research was guided by three broad questions: (1) How do leaders in successful secondary schools across different contexts respond to government systemic reforms? (2) What key challenges and issues do they face in sustaining academic standards for all whilst forwarding their broader educational success agendas? (3) How and to what extent do school leaders at all levels in these schools maintain a strategic and operational focus on the leadership of learning and teaching whilst managing wider structural and cultural changes?
The editorial in this special issue has provided an overview of this mixed-methods research. The design was based on but extended-conceptually and methodologically-two recently completed, parallel research projects led by the research teams, which investigated associations between the work of principals in effective and improved primary and secondary schools and the improvement of pupils' academic and social outcomes in the wider educational reform contexts in Hong Kong and England Walker, 2011). This article is based on the quantitative and qualitative research evidence collected from key staff in secondary schools in England only.
Quantitative evidence: Secondary analysis of the key-staff survey to investigate leadership and school process In the previous IMPACT (Impact of School Leadership on Pupil Outcomes) study, a national questionnaire survey was conducted for principals and key staff (two senior and/or middle leaders per school at primary level; five per school at secondary level) among a national sample of effective and improved schools in England. The purpose of the surveys was to explore principals' and key staff's perceptions of school improvement strategies and leadership actions that they believed had helped to foster better student attainment. The key-staff survey closely mirrored that of the principals so that comparisons could be made between responses by the two groups (Sammons, Gu, & Robertson, 2007).
Details of the sampling strategy for the IMPACT research were reported in our earlier publications (e.g., Day et al., 2011;Gu, Sammons, & Mehta, 2008Sammons et al., 2011). For the purpose of this article, we provide a brief summary here. An analysis of national assessment and examination data sets on secondary school performance was used to identify schools that were effective in their value-added results (which take account of pupils' prior attainment and background characteristics) and also showed significant improvement in raw results or stable high attainment over at least the previous three consecutive years under the leadership of the same principal. Approximately a third of the secondary (37%) schools (n=1,140) in England for which national data were available were classified as meeting our criteria as effective/improved over a course of 3 years. A total of 1,167 key staff questionnaires from 393 schools were returned, representing a response rate of 20% (out of 5,700).
The survey design was informed by a review of the literature on the impact of school leadership on student outcomes (Leithwood et al., 2006) and explored principals' and key staff's perceptions of change in six areas of school work: (1) Leadership Practice (2) Leaders' Internal States (3) Leadership Distribution (4) Leadership Influence (5) School Conditions (6) Classroom Conditions Detailed descriptive analyses of the principal and key-staff surveys were reported in Sammons et al. (2007). We conducted structural equation modeling (SEM) analysis of the questionnaire survey for principals that explored the relationships between leadership, school process, and changes in academic and other kinds of student outcomes (nonacademic areas such as engagement, motivation, behavior, and attendance over a three-year period (Day et al., 2016(Day et al., , 2014Sammons et al., 2011).
In this research, SEM analysis was conducted on data from the secondary key-staff survey in England. The purpose was to explore senior and middle leaders' perceptions of their principals' contribution to change and improvement in their schools. By comparing the key-staff SEM model with that constructed from the principal survey, we were able to explore whether and to what extent these senior and middle leaders shared similar views on how principal leadership operated to contribute to school improvement processes, conditions, and cultures and, ultimately, improvement in student academic performance in their schools. Specific attention was paid to examining the levels of consistency in perceptions between the key staff and their principals on the impact of school leadership, particularly that of the principal. SEM was chosen because it allowed the analysis to explore the latent structure of associations amongst survey items in terms of theoretical constructs.

Qualitative evidence: Case studies of four secondary schools
The qualitative strand used four in-depth case studies of a subset of the original 10 secondary casestudy schools in the IMPACT study . As we have outlined in the editorial, these four cases, together with the four in Hong Kong, were selected to enable in-depth, longitudinal analyses of leadership and change. All four schools showed significant improvement or higher than average in their value-added scores in English and mathematics at Key Stage 4 (age 16) in public GCSE examinations over the seven-year period prior to the commencement of this research (including the three years prior to the beginning of the IMPACT project). These case studies represented schools in different levels of socioeconomic advantage and disadvantage (as measured through the low-income indicator percentage of student intake eligible for Free School Meals) and ethnic diversity (Table 1).
Data were collected through two visits over a two-year period with detailed interviews of principals and a range of key staff and stakeholders. The main methodological advantage of studying these schools was that we were able to build on and extend existing datasets from the IMPACT study (2005)(2006)(2007)(2008)(2009) and thus achieve longitudinal narrative and reflective accounts of the challenges, processes, and outcomes of change and improvement that schools had experienced in mediating externally imposed structural and curriculum reforms across a period of nine years (2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014). By focusing on "success" (i.e., schools that had shown sustained improvement in academic performance over time and also were judged as Good or Outstanding by national inspections), we were able to identify effective principles and practices of leadership and educational practice for change and improvement in schools and classrooms. Through these, we extended our knowledge of how and to what extent some school leaders and teachers successfully mediate government models of systemic reform whilst maintaining the broad educational purposes of learning and teaching in their places of work.
Findings: How senior and middle leaders see their principals enact education policy for sustained improvement

Consistent views on synergy of leadership influences
The SEM analysis of the responses of secondary key staff derived from the main questionnaire survey (Gu et al., 2008;Sammons et al., 2011Sammons et al., , 2007 showed strong similarities to those by their principals, suggesting a high level of consistency in perceptions between key staff and their principals regarding both direct and indirect effects of leadership on a range of school and classroom processes that in turn predicted change (improvements) in schools' academic performance. In agreement with their principals, the key-staff SEM model also showed that sustained school improvement is built through the synergistic effects of the combination and accumulation of a number of values-led leadership strategies that are related to the principals' judgements about what works in their particular school context. Exploratory factor analysis followed by confirmatory factor analysis (CFA) was used to investigate the possible structures underpinning the questionnaire data from the key staff and to test theoretical models about the extent to which leadership characteristics and practices identified in the earlier literature review (Leithwood et al., 2006) could be confirmed from the sample of effective and improved schools in England. Results showed that the underlying leadership factors identified for the secondary key-staff survey largely accorded with the conclusions of Leithwood et al.'s (2006) literature review and the constructs identified in the principal survey. After deletion of missing data, the structural equation modeling (SEM) analysis was conducted with data for 1,054 senior and middle leaders from 309 secondary schools.
The SEM models predict changes (i.e., the extent of improvement) in student attainment over a three-year period for our sample of effective and improved secondary schools as the dependent variable. They demonstrated that the leadership constructs identified in the literature operated in ways in which we hypothesized in relation to influencing directly and indirectly a range of school and classroom processes that, in turn, predicted changes (improvements) in schools' academic performance. These dynamic, empirically driven models present new findings on the impact of principal leadership of a large sample of effective and improving schools in England on change in student outcomes, and thus add a dimension to school-improvement and leadership theories. The approaches used to conduct exploratory and confirmatory factor analysis and explore the key-staff SEM model are identical to those used for the principal surveys, which were reported in detail in the final IMPACT project report and other subsequent publications (Day et al., 2016(Day et al., , 2009Sammons et al., 2014Sammons et al., , 2011. Because of the limited space in this article, we use the key-staff and principal-SEM models to illustrate that in successful schools there are broadly consistent and coherent understandings by leaders at different levels regarding how leadership practices and strategies work to influence the conditions for and outcomes of school improvement. The secondary key-staff SEM model of leadership practice showed a relatively high internal consistency reliability of 0.81 (Figure 1). The model fit indices (χ2 = 5137.632, df = 1258, χ2/df = 4.084, p < .000; RMSEA = .054, 90% CI = .053~.056; CFI = .871; TLI = .859) suggest a "good" model-data fit (Kaplan, 2004;Kline, 2010). All latent variables were derived from the CFA. Appendix 1 lists the observed variables (i.e., questionnaire items) that are associated with the latent constructs in the model. While all the links between the different latent constructs were statistically significant (as indicated by the t values at p < .05), some were stronger than others. The strength of these connections indicates which features of leadership practice were found to be most closely linked for respondents to the surveys in the 309 secondary schools. Figure 2 shows the SEM model for secondary principals (Day et al., , 2016. Both the principal and the key-staff SEM models align by revealing that school processes directly connected with principals' leadership strategies are the ones that also connect most closely with improvements  in aspects of teaching and learning and staff involvement in leadership; these in turn help predict improvement in school conditions and cultures, and so, indirectly, improvement in student outcomes. Also, in both SEM models four groups of latent constructs were identified (as indicated by different shadings in Figures 1 & 2) as predicting change in student attainment outcomes. They are positioned from proximal (i.e., factors that are near to principal leadership and influence directly constructs such as "developing people" and school conditions) to distal (i.e., factors that are further removed from principal leadership and influence indirectly the intermediate outcomes such as pupil behavior and attendance). They represent robust underlying dimensions of leadership and school and classroom processes (i.e., latent constructs relating to key features of leadership practice and school and classroom processes) and highlighted strategies and actions that school principals and staff had adopted to raise student attainment.
These groups of latent constructs, driven by theories of school leadership and school improvement, were identified in the process of model building. As the two SEM models show, the leadership practices of the principal (Group 1 dimensions) and of the SLT (Group 2 dimensions) influence, directly or indirectly, the improvement of different aspects of school culture and conditions (Group 3 dimensions), which then indirectly influence the change in student academic outcomes through improvements in several important intermediate outcomes (Group 4 dimensions). The latent constructs of leadership practices and school conditions and the relationships identified in the two SEM models are broadly similar, suggesting a marked consistency in how leaders at different leadership levels perceive the ways in which principal leadership had made a difference to the academic performance of their schools. However, there are also differences in each of the four groups of latent constructs, suggesting that the key staff valued, in particular, leadership practices that created collaborative learning environments to support teachers to improve the standards of their teaching.
• Group 1 comprises key dimensions of principal leadership. The three key dimensions in both key staff and principal models are the same: Setting Directions, Redesigning the Organization, and Principal Trust. Also, in both models Developing Teachers is closely linked with the first key latent construct, Setting Directions, suggesting that for senior and middle leaders, leadership practices to promote all staff's learning and development are also perceived as central to the improvement priorities of their schools. A major difference in the key staff model is that a greater emphasis was placed on principals improving the environment for and practices of teaching and learning. Two additional dimensions of Creating an Environment for Raising Achievement and Managing Teaching and Learning Practice were strongly linked with the first two key latent constructs respectively. • Group 2 comprises dimensions in relation to leadership distribution in the school. The four dimensions in the principal SEM (Distributed Leadership, Leadership by Staff, Senior Leadership Team (SLT) Collaboration, and SLT's Impact on Learning and Teaching) point to a wider and deeper distribution of leadership across the school. In contrast, there are only two latent constructs related to leadership distribution in the key-staff model indicating a strong emphasis on the distribution of principal leadership to senior leaders in the school. • Group 3 in both models comprises four dimensions relating to improved school and classroom processes and environments that function as mediating factors in the models. Three of the four latent constructs are conceptually similar, which together emphasize the importance of improving school conditions, promoting teacher collaboration, and using assessment to improve learning. The only difference is that the fourth dimension in the key staff model still has a strong within-school focus on high academic standards, whilst the principal model points to an external dimension of External Collaborations and Learning Opportunities. • Group 4 in the principal model comprises four dimensions: High Academic Standards, Pupil Motivation and Learning Culture, Change in Pupil Behavior, and Change in Pupil Attendance. These constructs identify important intermediate student outcomes that had direct or indirect effects on measured changes in student academic outcomes over three years. In contrast, for key staff the most important intermediate latent construct identified relates to Schools' Disciplinary Climate. It is possible that key staff in secondary schools are particularly affected by this feature of their school's culture .
Despite some differences in the two SEM models illustrated above, both demonstrate the "synergistic influences" of principals' leadership practices that "may be promoted through the combination and accumulation of various relatively small effects of leadership practices that influence different aspects of school improvement processes in the same direction, in that they promote better teaching and learning and an improved culture," especially in relation to schools' disciplinary culture (Day et al., 2016, p. 18). In both models, such synergy of leadership influences begins with principals setting directions and restructuring the organization (Group 1) to promote teacher development and support the improvement of teaching and learning. Building trusting relationships with teachers and the senior leadership team (Group 1) was shown to be another key leadership strategy that was perceived to have enabled the distribution of leadership within the school (Group 2), and, through this, the transformation of the social and relational conditions of schools (Group 3). Thus, although the specific strategies to achieve these may be emphasized differently in the two models, the relationships between key leadership practices, school improvement processes, and changes in student outcomes identified in both models are broadly similar.
Although of value in identifying patterns and testing hypothesized relationships between a range of interconnected leadership actions and strategies, on their own, these SEM quantitative analyses have limitations given the nature of the survey items and numeric data they generated. They could not reveal what kind of leaders these principals were or how they were perceived by their colleagues. Nor could the SEM illuminate the different ways in which combinations of strategies were applied by principals in particular contexts and at particular times, and the reasons for this. Evidence from the case-study investigations provided complementary, rich illustrations and insights as to how principals led their schools to respond to multiple external policy demands and how the "synergistic effects" of different leadership practices on students' academic outcomes were achieved. The use of mixed methods thus enabled deeper insights and explanations to emerge.

Building capacity: Using policy as impetus for change
The four case-study schools served communities of contrasting socioeconomic disadvantage and were led by principals with different years of experience in the school. However, despite differences in context and leadership history, what shone through the interviews with senior and middle leaders in all four schools was a strong, collective sense of positive leadership which embraced external policies and innovations as the catalyst for further growth and higher performance.
For the purpose of this particle, we have selected a story of a secondary school that provides an example of how the principal led an already successful school to even higher performance. This principal had the shortest tenure of all the principals in this research, having only been in post for three years when the first data were collected. Her values and vision for excellence were perceived by senior and middle leadership as the key drivers for change. Shaw Lane was inspected within a term of her appointment and was judged to be a "Good" school. Since then, she had made considerable progress in addressing the areas of weakness the inspection had highlighted, most notably the teaching and learning agenda which had been radically overhauled via a range of strategies to foster more collaboration and creativity amongst teachers. We interviewed seven senior and middle leaders in the school and most were interviewed twice over this two-year project. This example is used to illustrate that for principals in our case studies, the key to success in enacting external policy demands is to use them as opportunities to develop and transform people-such that they share the same values and passion for further growth and development, and that they become change actors (as opposed to receptors) who possess enhanced knowledge, qualities, and capacity to regenerate the social and intellectual culture of the school, and importantly, to manage new changes, collectively and collaboratively, for unified goals and core purposes.
The Shaw Lane girls academy: From Good to Outstanding

Context
Shaw Lane, a single-sex school situated on the outskirts of a large urban area within the Midlands region of England, was a relatively small secondary school and sixth form that provided an education for approximately 800 students between the ages of 11-19. The school served a culturally homogenous population with the majority of students from a non-White heritage background and many speaking English as an additional language. The number of students eligible for free school meals was higher than the national average (46% versus 13%), as was the proportion with a special educational need (75.9% versus 16.2%) at the time the study was conducted.
The school was judged to be a Good school by the Office for Standards in Education (Ofsted) shortly after the principal's appointment in 2011. The inspection report drew attention to the good progress made by all students and the high-quality teaching and learning that took place across the school. It also highlighted the positive impact of the recently appointed principal within the context of the "legacy of underperformance" she inherited from her predecessor. By 2014, the school achieved an overall grade of Outstanding.
During this critical period of school improvement and renewal (2011)(2012)(2013)(2014), four major new government initiatives were introduced to schools in England, reflecting a change of government in 2010-all of which demanded deep structural, financial, and cultural changes: performance-related pay and appraisal (Department for Education, 2013); a new Ofsted inspection framework; a review of the National Curriculum and change in the way school performance was measured; and pressure for the academization of all schools (which are funded by the Department for Education but independent of local-authority control). The principal's aspiration for Outstanding was proudly shared by her staff as a "powerful" aim and morally just vision for the school (Assistant Principal). Driven by such an aspiration, she used the enactment of these various external policies as an opportunity to raise expectations and anchor core values; to consolidate consultation and enhance ownership of change; and, above all, to build, broaden, and deepen the capacity required to lead further change and improvement.
Opportunity of purpose: Anchoring core values Deal and Peterson (2009) argue that "Central to successful schools is a powerful sense of purpose that is focused on students and learning" (2009, p. 250). Shaw Lane was no exception. All the senior and middle leaders reported that the school positioned itself ahead of educational policy and that they were cautious of being too reactive toward government reform. Managing change was seen pragmatically as the nature of the job: "When a policy comes in-if it's statutory-then it's got to be done" (Head of Mathematics). Because government policy initiatives were, more often than not, unpredictable and potentially transient in nature (seen as likely to shift with a change of government), it was believed that the priorities of the school had to be centered on moral purpose, upon doing: what is right for the students because if you do what is right for the students then you must be doing the right thing. . . . At the end of the day, if you look at government policy it comes and it goes, doesn't it? But the needs of the students don't change that much; they might change in terms of the contexts they have but, fundamentally, what you're trying to do is to prepare them for a future in which they can be useful citizens. (Senior Deputy Principal) Such moral compass defined a shared direction for the school and a strong commitment in the staff who wanted to move the school forward "to be more than Outstanding: making sure that whatever we are doing is for the benefit of the students" (Middle Leader-Humanities). What also came across consistently and powerfully here was how the shared purpose and direction had run deep to shape a confident attitude toward change and policy demands. Student needs rather than government priorities informed the way that the school was organized and operated: I don't feel shackled by policy because I've got a lot of experience behind me and [the principal] wants Outstanding and so she is putting structures into place to achieve that; and that is why I don't feel shackled by it because if you are doing your job right then you have nothing to worry about. And we share a similar ethos which is about producing well-formed individuals and it's about us finding the best way for these girls in Shaw Lane to achieve and to be well-formed individuals. So [the principal] will do that her way. (Assistant Principal) Associated with this positive mindset of change was a sense of positive, assertive, and responsible professionalism in the school. The ethical principles and standards that acted as drivers for improvement were to "do your best every time a student comes through" because "every student who comes to this school has only one chance" (Senior Deputy Principal). Importantly, these standards were defined, believed in, and pursued by the staff, manifesting themselves in the form of what Elmore (2003) calls "internal accountability": At the end of the day, what you are trying to achieve for the students is the best possible exam results and qualifications that are going to enable them to go on and be successful in the future; and you want the students to have the qualities and the characteristics which will enable them to be productive citizens when they leave here. If you can do all of that then whatever accountability framework comes along it should meet it, shouldn't it? If you're doing what is right for the student, then it should meet whatever framework does come along.

Opportunity of ownership: Communication and consultation
The principal and her senior leadership team created clear lines of communication to ensure that staff members were thoroughly consulted and well informed about the policymaking process at school. They were given ample opportunity to air their views on the ways in which the latest policy initiative would affect them and their work. This process, driven by the principal's insistence on communication and transparency, also ensured that staff members fully understood the policy in question and that they were given time to negotiate how it would be enacted on the ground in their departments and classrooms: Mostly the senior team is very good and they will consult with middle management and we have a group set up where we will meet up at lunchtimes or after-school sessions where, if the senior team have got certain policies that they are going to implement, they will take our views on board before they implement the policy. So, there is that going on and we, as heads of department, meet regularly with the senior team and, of course, those issues are discussed there as well and heads of department will get a chance to have their say as well. So that level of communication will go on before that policy is actually put into practice, so it's not something that has just been sprung on us and there is a certain amount of discussion and communication that goes on beforehand.
(Head of Mathematics Department) There was also a forum for departmental heads to discuss the implications of policy changes through their monthly curriculum meetings before returning to their respective faculties to feedback these discussions to their teaching staff and consult them on any changes that might have been proposed.
The following senior leader explained how the organizational structure had facilitated communication and the sharing of information, which helped them to manage change in practice: ICT is no longer a topic in itself-it's changed to computer science-and we were looking at that yesterday and whether we can do an ICT audit across our curriculum because every subject is responsible for teaching ICT. This is what the government is saying and we need to adjust to these changes. So, it's in curriculum meetings and it's in faculty meetings as well because when we go back we discuss it as a faculty on the necessary changes that are taking place. Even the changes in the courses for GCSE now are fed down from senior management and then passed through so that everyone is aware of what is going on across the school. (Acting Deputy Principal) It is perhaps, then, no surprise that a strong sense of ownership and collective loyalty was shared in the school. This was seen as a sign of an open, cohesive, and trusting culture that the principal and her senior leadership team had regenerated. Shaw Lane was described by middle leaders in particular as a "happy place" where staff were treated well (Head of Humanities) and "a listening school" where "I've got a voice": "You've got the freedom to say what you are happy with and what you feel might need to be improved" (Head of English). Making policies was regarded as "a whole-school thing" (Head of Humanities), as the decision-making process involved open discussions with staff members at every level in a very democratic way. As a result, there was a high level of consistency in behavior across the school: "Policies we have integrated are whole school policies. It's almost like nobody deviates from the norm and we are all doing the same thing: the marking policy is the same; the data collection is the same; behavior policy is the same" (Head of Humanities). Such consistency in behavior and vision helped to deepen the coherent and cohesive culture in the school, which made further growth and improvement possible.
Opportunity for capacity building: Focusing on the basics Improving teaching and learning was seen as "the bread and butter of what we do" (Assistant Principal), and was believed to be "a positive drive" (Head of Music) that had turned the school around: That is all about capacity building and it's all about developing the staff to have the skills and knowledge that they need and that is obviously going to feed through to the students and lead to them getting a better experience. (Senior Deputy Principal) Put simply, to embrace change effectively in the school required capacity building. Key in this regard was quality professional development. This was because, at least in part, the policy "is actually saying that this is the direction that we think you ought to go, and this is the sort of path we want you to take. But how you walk along the path-'how the garden grows'-is actually up to you" (Senior Deputy Principal). Thus, knowing how to make sense of external policy and recontextualize it in ways that were fit for purpose required sustained attention to improve the knowledge, skills, and practices of the staff on the ground. The newly introduced Ofsted inspection framework, for example, was used as a vehicle to raise the standards of provision of teaching and learning in the school. This was achieved through the provision of a series of in-house training events designed to ensure that the staff had a thorough grasp of this framework. At the same time, there was an "Open Door Community" (Assistant Principal) in the school where the staff felt "safe" to share practice and discuss what outstanding teaching and learning looked like. After some initial worries, the Head of Humanities realized that the new framework had not really had much impact on her "because our lessons are well-planned and we are well-resourced anyway." Similarly, when enacting the new performance-related pay and appraisal policy in the school, efforts had been focused on how this policy could be used to join up with support for learning and development, and through this, foster a professional culture of high expectations.
We've also looked at the idea that performance management is something that underpins what happens throughout the whole school. So your performance management should be tied to your CPD and your school development plan, and so every department, having identified what the department needs are to fit in with the whole school development plan, is able to create a training plan for the department and, therefore, the CPD will actually support individual staff in specific CPD that will help them meet department needs, their own needs, and whole-school needs. (Senior Deputy Principal) The leadership intention was well-received by their middle leaders: "they've [Senior Leadership Team] really pushed the idea that performance management is not a whip for us to be beaten with and it's meant to be about self-development" (Assistant Principal). The quote from the Head of Mathematics below expressed a similar view, which represented not only a common voice from the interviews, but also, and importantly, a testimony to the success of the principal leadership in that she had shaped a high degree of consistency in values, expectations, and behavior across the school. I think colleagues understand the need for accountability. You would think that there are very few colleagues who are in that position where they are bordering on being incompetent, if you like. The majority are hardworking and conscientious people who want to do right by the kids. So, the idea of the appraisal system is to support them to improve and it's just about evidencing what you do day in and day out. That's what needs to happen really: it's finding out the people who are perhaps dragging their heels and making them more aware and more accountable and getting them to perform to their best. (Head of Mathematics)

Discussion and conclusion
A central concern of this research was to explore whether, and in what ways, various senior and middle leaders had a consistent understanding of how their school principals purposefully incorporated and embedded, rather than were passively led by, external policy demands in sustaining school improvement and growth in student learning over time. The findings of the research led to two observations.
The first observation is about principal leadership. Evidence from our research suggests that building internal school capacity for improvement is not a simple, linear process. It requires directions from inspiring and visionary school leadership to create, develop, and sustain coherent and fit-for-purpose structures, cultures, and conditions to grow the knowledge, skills, and commitment of individuals and harness them to become the collective capacity of the school. This observation confirms what we already know from the research literature on successful school leadership: shared directions and goals and consistency in understandings of the standards of teaching and learning are key characteristics of high-performing schools where fundamental principles and values unite and drive teachers and leaders to be intellectually and emotionally committed to make a positive difference to the lives of their students Drysdale & Gurr, 2011;Gu, Rea, Hill, Smethem, & Dunford, 2014;Klar & Brewer, 2013;Leithwood et al., 2006Leithwood et al., , 2010Sun & Leithwood, 2015b).
Investigating how successful principals had managed external policy demands from the perspectives of their key staff enabled us to learn more about leadership and change. In high-performing schools a key defining aspect of principal leadership is an unrelenting focus on fostering consistent values, expectations, and standards, and through these, empowering and transforming staff capacities and organizational conditions to embrace change and improvement. A growing body of research on senior and middle-level leaders, albeit limited, has shown the importance of their roles in influencing decision making, supporting the professional development of their peers, promoting shared vision and high expectations, developing a culture of shared responsibility and trust, and fostering collaboration at different levels within and across the school (Cranston, 2009;Dinham, 2007;Gurr & Drysdale, 2013;Leithwood & Riehl, 2005;Shaked & Schechter, 2018;Wenner & Campbell, 2017). Put succinctly, senior and middle-level leaders hold a key position in schools' efforts to manage change, embed innovation, and sustain improvement. However, the extent to which they are able to fulfil their leadership roles and responsibilities effectively and consistently is influenced, directly and profoundly, by the leadership values, qualities, and practices of their principals Gurr & Drysdale, 2013).
In this research, the marked similarities between the principal and key-staff SEM models, together with the narrative accounts from the case-study examples, highlight-most powerfully-that establishing consistency and coherence in school structures, cultures, and improvement processes holds the key to engaging the heads, hearts and hands of the school community to achieve sustained and sustainable performance over time. Such consistency and coherence were reflected in understandings-between those who led and those who were led-of how and why their schools were able to become successful and, as importantly, to stay successful. They helped to shape the day-to-day practice of school life and enabled schools in our research to remain focused on the core business of schoolsquality provision of teaching and learningirrespective of external pressures of change.
The second observation is about how successful principals respond to, manage, and enact external policy demands. We found, as in the other articles in this special issue, that in successful schools the process of policy enactment and the process of school improvement are not two separate processes. They are intertwined to form one overall process in which external policy initiatives and internal school improvement practices are purposefully aligned by principals to serve their moral purposes, educational values, and goals for the school. At the heart of this intertwined process are continuous leadership efforts to support collaborative professional learning and development and, through this, to build the necessary whole-school capacity for sustainable personal, social, and academic improvement in student outcomes. Investigating how school principals shape their school's improvement efforts from the perspectives of middle and senior leaders provides us with more insightful evidence on how and why some schools have the capacity to manage change, despite facing the same external challenges and demands, whilst others do not.
In summary, policy enactment is, in essence, about change. External policy initiatives-whether they are foreground or background noises that schools can or cannot ignore-represent some, but not all, of the many demands, challenges, and opportunities that schools face in their everyday working worlds. Enacting policy successfully essentially relies on building and consolidating the capacity for further growth and development. Key in this regard are strong leaders who know how to design the social and intellectual conditions which engage the heart and mind of individuals in the school and, through this, harness their ideas, experiences, knowledge, and relationships to fulfil shared values and achieve shared goals. Kotter (1996) argues that although managing change is challenging, the much better challenge for most organizations is "leading change" (1996, p. 30). Evidence from our research shows that in successful schools, what the leaders appear to be doing exceptionally well is using policies and reforms as opportunities for change-purposefully, progressively, and strategically-to regenerate collaborative and coherent cultures and conditions which encourage and support the staff to learn, to reflect, and to renew their practice. Note. SEM = structural equation modelling; CPD = continuing professional development; SMT = senior management teams; SLT = senior leadership teams.