s the election campaign gears up, there has been much sniggering about David Cameron’s decision to subject himself to the fearless inquisition of Heat, a celebrity magazine best known for its obsession with Katie Price and The Only Way is Essex.

Rather than asking about zero-hours contracts, Heat quizzed the PM on whether he knows all the words to Let It Go (yes), his phobia (rats) and the ability to multi-task (“I’m a man. I can’t do two things at once!”).

Cameron, sneered his critics, was taking the easy option. But I’m not so sure. Grumpy Paxman or incredulous Humphrys may seem more threatening, but history is littered with examples of politicians undone by seemingly innocuous interviewers.

It was, after all, the queen of sofa TV Fern Britton who coaxed out of Tony Blair the admission that he thought it would have been right to invade Iraq, even if it had been known there were no weapons of mass destruction. Margaret Thatcher’s attempt to show Eighties teenagers her caring side was scuppered by telling Smash Hits magazine that her favourite song was that hymn to free market economics How Much Is That Doggie In The Window?, while David Mellor’s status as national heritage secretary was hardly helped when he told a journalist his favourite track from Sgt Pepper was “Submarine” (presumably he meant Yellow Submarine, which is on a different album altogether).

The aggression of our master interviewers rarely results in a palpable hit; if anything, it induces sympathy for their prey. But offguard and relaxed, politicians can make a fatal slip. Cameron may yet regret the shocking disclosure that he is proud of being distantly related to Kim Kardashian.