I was struck by the context in which one of the survey's compilers placed Tony Blair's third-placed finish. He tells the FT that, "Tony Blair’s performance as prime minister is clouded by his decision to take part in the Iraq war … Almost two thirds of academics say this was his biggest failure. No other prime minister since 1945 has one issue so closely associated with their reputation." That could say more about the respondents' pre-formed opinions than anything else, but you do wonder whether the history books will really see Iraq as Blair's defining act.
Anyway, here's the FT's graphic for your delectation: