David Cameron made a classic Freudian slip during a question and answer session this morning.

David Cameron: "This is a real career-defining (err) country defining election..." pic.twitter.com/gAavS9Sgjb — Adam Bienkov (@AdamBienkov) May 1, 2015

It's a particularly revealing slip because it appears to confirm what so many critics of Cameron have always said. When he was once asked why he wanted to be prime minister, he famously replied that "I think I would be good at it".

Ever since then he has been accused of lacking any real vision for what he wants to do in the job. The allegation has always been that it is his dedication to his career, rather than any ideological or political drive, which keeps him going.

It also chimes with more recent accusations that he is risking the future of the union by talking up the SNP, in order to cling on to the keys to Downing Street.

But most of all, today's verbal slip-up is a reminder that Cameron could be out of a job in just a matter of days, unless the polls dramatically change.

And if he fails to cling on, he will go down in history as the Conservative leader who could not win a majority against either Gordon Brown or Ed Miliband. For David Cameron, this really is a career-defining election.