My cousin David Cameron

Much has been made of Cameron's time, alongside Boris Johnson, in Oxford's Bullingdon Club, later joined by George Osborne (and me, incidentally). Bullingdon membership is no key to political success but it is a sign of a desire for popularity, and an ambition to be voted into clubs, whether it's a university drinking club, or the House of Commons. And Cameron was certainly clubbable at Oxford – in 1987, he was president of the Gridiron, another university social club – where he had been less so at Eton. 'He didn't get into Pop [Eton's club of the most popular boys] because he so wanted to get in,' says one of his old teachers. 'I think that's why he was so keen to get into the Bullingdon.'

Cameron's political persona was really hammered out, though, not at Oxford, but in his days in the Conservative Research Department, after leaving university in 1988. 'People think Cameron and Boris are the same because of Eton, Oxford and the Bullingdon,' says Andrew Gimson, Boris Johnson's biographer. 'But Boris is really an anarchist, and Cameron is the ultimate insider. People bang on about the Bullingdon but a few drunken nights is nothing compared to years in the Conser-vative Research Department. He's the Establishment man writ large – he will always do what the Establishment thinks prudent.'

It was while working in the Conservative Research Department in his twenties that Cameron first sketched out his plans for a political career. 'He always had his eye on the main prize,' says Hywel Williams. The signs of his toughness and confidence were apparent even then. 'He was quite Eighties in his brashness – a sort of damn-your-eyes brashness,' says another special adviser. 'He had a much grander manner and voice then, too. He's had to get rid of that since. And he was very con-fident. Every week, us special advisers would meet in the Cabinet Office with Jonathan Hill [John Major's political secretary], around that great table. We'd meet at 1pm, and stay until 2.30pm, and Jonathan Hill would often not order any lunch. Cameron thought, "Sod this," and would turn up with a pile of sandwiches and munch through them.'

That confidence is allied to charm and manners. In my five years as deputy comment editor of The Daily Telegraph, he's the only person who ever sent me a thank-you letter for being asked to write a column.

'He's extremely good at flattery,' says Andrew Gimson. 'He made a point of coming up to me to say how much he'd laughed at one of my articles. He's got extraordinarily good manners. At an event with the Chelsea Pensioners recently with Boris, one of the pensioners fell over and got stuck behind a fence. No one noticed, but Cameron immediately rushed over, even though he was in the middle of talking to the Lieutenant Governor. "Sir, can I help you?" Cameron said to the pensioner.'

Other journalists talk about how his manners can be selective; how he can be abrupt to unimportant people; how he doesn't say thank you to minor operatives. 'He's not like the other Tory MPs,' said one political journalist. 'He never gets drunk. He had me round to dinner and was friendly but patronising. He's really an old-fashioned patrician. That's what Old Etonians are like these days: they used to be shambolic, and now they're very competitive, under a thin veneer of self-deprecation.'

Cameron's staff won't hear a word against him. He's had a close-knit team ever since he won the leadership in 2005. 'He inspires leader-worship in lots of us,' one senior Tory adviser told me. With the press on the battle bus, he keeps up a steady supply of cheery banter throughout the day, occasionally dropping into the chorus of Take That's 'I Want You Back', after our morning with Gary Barlow. 'Sam gave me a congratulatory kiss after the debate,' he tells us, leaning on the headrests either side of the aisle, as we trundle through North Wales. 'But the rest of the evening will remain confidential, part of the
marital contract.'

While he teases in conversation, in his speeches he goes in for self-deprecating humour. He introduces Gary Barlow in Nantwich by saying, 'Last night, on the telly debate, I sometimes felt I was part of Britain's worst boyband. That's why I am so pleased to share a stage with a member of Britain's best-ever boyband.'

The banter only breaks down into a flash of tetchy anger once, when a lobby journalist asks him about the narrowing polls. 'My job is to move the dial, not to set the pointer,' he says, not quite snapping, but almost. And what will happen if the dial doesn't move?

'If he loses, he'll return to his life with Sam, and things won't change much,' says one old friend. 'Other politicians' personal lives are far more dependent on their careers. He defers to no one professionally, except perhaps Kate Fall [his deputy chief of staff] because she's the gatekeeper. And he defers to Sam; she's got an inner steel.'

And so has Cameron. The Steel Lady – and her Steely Husband – will be OK, whatever happens next Thursday.