Cameron is undone by a broken pledge in his Sky "debate"

One of the worst aspects of modern day political leadership must surely be the need to go and be ritually humiliated by television debate audiences.  You have to give a wan little smile at the voluble English Literature student who spends ages asking her incoherent and roundabout question, only to finish her inestimable waffle with an accusation that you are the terrible waffler.  You have to listen to the grumpy man who wants to know why you need trade agreements when you've got amazon and ebay.  People who have read a couple of Express front pages suddenly become the interlocutary experts you have to politely respond to.  Lose your rag and you become vilified forever.  Stand there and respond with reason, to often unreasoned questions, and you just look like a wimp and everyone can proclaim that the wonderfully well informed audience sorted you out.  It's an unwelcome gig, but it's a cost of democratic leadership.

David Cameron is, as one commentator has put it this morning, an old trouper in this regard and he kept his cool while under fire from the audience at last night's Sky News debate, responding passionately yet reasonably, and staying on what was a relatively clear message throughout.  Whatever you say about Cameron's aloofness, his rarefied upbringing or his isolation from the lifestyles of most ordinary people, you have to respect the fact that he does these amongst the people things well.  He engages, I don't think he patronises, and he really does try and explain his stances.  Most of us would lose it early on, if we even had the patience to go through with such a process.

Where Cameron was genuinely on the ropes, however, was at the beginning, at the hands of an experienced political observer and interviewer, Sky's Faisal Islam.  Still relatively new to his position as Sky's political editor, there seems to be a general agreement that he emerged with his reputation enhanced.  Tenacious, appropriately aggressive and with a nice ability to use humour to puncture his subject, he looks as if he might be able to fill a Paxman-esque void in political interviewing (though still behind the current past master, Andrew Neill).

It was Islam's question about immigration, and specifically Cameron's oft-quoted pledge on limiting immigration, that gave the Prime Minister the most trouble.  Not surprisingly either.  It's a pledge he hasn't met, and can't meet.  Whatever other points I might want to disregard from the shrill and constantly whinging Leave campaign, the one about his pledge undermining trust in politicians hits home.

Pledge breaking is the worst thing a politician can do, which is why it is concerning that they seem so free with making them.  Cameron's old coalition buddy Nick Clegg fell the same way with his broken pledge on tuition fees.  I'm surprised Cameron got caught by this.  Feeling pressurised from the right, worried about the inroads made by immigration-hating UKIP, he allowed himself to appease their cries with an impossible pledge.  Now he's paying the price, and it's a pity because in many ways Cameron is a reasonable man, a pragmatic political leader and a man who can give politics a sheen of authoritative respectability.  An ill thought out pledge, a short-term response to a difficult and intractable problem, has undone him.

David Cameron tried to present an honest case about continuing membership of the EU to his studio audience last night.  The easy accusation of a non-listening young audience member that he was "waffling" wasn't actually true.  The pity of it was that he hasn't been as honest about the EU and about wider problems - notably immigration - before.  Truly, politicians who frame their dialogue in the transient window of 24 hour news and social media find that ignoring the long view can have dire consequences.