We compare measures of the tone of parties’ campaigns in the 2015 General Election in England, based on, respectively, coverage of parties’ campaigns in six national newspapers, citizens’ perceptions, and expert judgments. It is the most extensive study of such measurements outside the United States and one of very few to include expert judgments. We find that citizen perceptions and expert judgments are heavily affected by partisan bias. We show how these biases can be eliminated with a regression-based procedure. After such adjustment, seven of the eight resulting measures of parties’ campaign tone (five based on newspapers, one on citizen perceptions, and one on expert judgments) are strongly correlated. The eighth measure (based on one of the newspapers) depicts the tone of parties’ campaigns very differently owing to different criteria of what to cover in a campaign. Each of the three kinds of empirical information is adequate as a basis for measuring parties’ campaign tone, but adjustment for partisan biases is essential for perception and judgment data. Common apprehensions about the “subjectivity” of citizen perceptions are not justified, while expert judgments are equally useful, as long as sufficient information is available to eliminate their partisan bias.