This article analyses the nature of the support given to the candidates in the 1975 Conservative leadership contest, in which Margaret Thatcher replaced Edward Heath. In contrast to the orthodox account of the contest – which interprets it as largely non-ideological – the article argues that there were clear ideological forces at work. The right strongly supported Thatcher in both rounds; the left strongly backed Heath and then Whitelaw. Region, experience and education also influenced the voting. The traditional accounts, which explain those voting for Thatcher as doing so simply because she was not Heath, have, therefore, to explain why only certain types of MPs felt this way. Margaret Thatcher may have won because she was not Ted Heath; but she did not win solely because she was not Ted Heath.