The question they dreaded in the court of David Cameron was looming. If asked, it could scupper the young Tory's chances of leading his party - and maybe even end his political career: "Have you ever taken class A drugs?"
His leadership rival David Davis gave a straight "no" when asked at the hustings in Westminster in 2005. Kenneth Clarke raised the stakes by adding, unprompted: "If it's of interest to you, I have not taken cocaine."
His answer was a nod to rumours sweeping the House of Commons that Mr Cameron, the new darling of Tory modernisers, had snorted the drug while working in the media hothouse of Carlton Television - and possibly even as a special adviser at the Home Office. Next up to face the rightwing '92 Group of backbenchers that afternoon in October was Mr Cameron himself. There seemed no hope of avoiding a statement on drugs that could haunt him for ever.
But the question was never asked. Not for the first time - or the last - Mr Cameron had been protected from answering enquiries about his past. The full story of how he was spared that scrutiny, told for the first time today, emerges as the pressure grows for him to come clean about his involvement with drugs.
The question has not gone away - and the possibility of it being deflected for ever by the tight circle of friends around him is diminishing fast. The fact that he smoked cannabis as a 15-year-old, revealed in this newspaper last Sunday, has led to renewed demands that the Tory leader give a full account of which illegal substances he has used and when.
"David Cameron says law-makers must not be lawbreakers - but a special adviser to the Home Secretary makes more drug laws than most MPs," Lord Oakeshott said yesterday. The Liberal Democrat peer was special adviser to Roy Jenkins when he was Home Secretary. "Cameron must just tell us when he stopped taking illegal drugs, not hide behind his shifty soundbite."
His remarks follow those of Kitty Usher, a ministerial aide to Margaret Hodge, who broke the Government's silence on the subject last week: "I suspect the real reason he is not commenting is because he has refused to deny much more serious allegations about hard drug use and doesn't want to come clean about that."
So far Mr Cameron has stuck firmly to his strategy of refusing to answer questions about a "private past" before he became an MP in 2001, although it is unclear whether he means this to include his earlier time as an adviser. Such stonewalling may keep reporters at bay, but his own Tory MP colleagues are a very different matter.
The plot to confront Mr Cameron with a direct question about cocaine was hatched at a meeting of David Davis's campaign team on the morning of 12 October 2005. With his own bid for the leadership flagging, Mr Davis knew the issue of drugs was his best hope of getting back on equal terms with the new front-runner.
Among the Davis supporters who gathered that day in the House was the newly elected MP Mark Pritchard. Just who came up with the idea of ambushing Mr Cameron at the '92 Group is not known; one person present suggests a "corporate view" was taken. In any case, it was Mr Pritchard who put the class A question that afternoon.
But Mr Cameron had been warned in advance of what he might expect, by another Davis supporter, David Ruffley. A special adviser in the John Major government at the same time as Mr Cameron, he was appalled at what he considered a "dirty trick".
Mr Ruffley secretly promised a leading lieutenant in the Cameron camp that he would try to foil the plot. Quite what happened next is a matter of dispute. Witnesses at the time saw Mr Ruffley and Mr Pritchard engaged in heated debate in a corridor near where the hustings were taking place, but the latter denies absolutely that he was "leant on".
What is not in dispute is that Mr Cameron was not asked directly before his peers whether he ever taken any class A substances. A softer question on drugs was asked by another MP, which would have made it very clear that a follow-up was not just a routine enquiry. But Mr Pritchard was silent.
There was also silence about the Eton story until it was revealed by Independent on Sunday writers Francis Elliott and James Hanning. Their book suggests that Mr Cameron continued smoking cannabis at Oxford, albeit infrequently and in moderate quantities, after being confronted by his headmaster.
Despite distractions he got a first in politics, philosophy and economics at Oxford and joined the Conservative Research Department, eventually working in the Treasury and the Home Office. If he did take cocaine or any other class A drug during this early stage of his career he has been remarkably well-served by any fellow users. As public affairs manager for Carlton Television, a job for which he was headhunted in 1994, he might have been exposed to drug-taking individuals. But Mr Cameron either abstained or was circumspect with whom he indulged, write Elliott and Hanning. The future Tory leader stuck to lager at TV industry gatherings where "cocaine use is hardly unknown".
His private world would seem largely immune to the charms of tabloid cheque-books, given that his schoolboy friends in the exclusive Bullingdon club went on to become bankers, hedge-fund managers and pillars of the Establishment. Not the sorts to spill the beans for money.
He is better off, therefore, than the shadow Chancellor George Osborne, whose social circle as a young man was much wider. His friendship with a woman he knew in 1993 as Natalie Rowe came back to haunt him in October 2005 when the former prostitute alleged he had taken cocaine with her. Mr Osborne denied the drug claims, but had to admit he had known Ms Rowe. It was precisely the sort of "kiss 'n' tell" that Mr Cameron's upper-class set would never dream of.
But as his profile grows there are now some places where not even moneyed or influential friends can help him - such as the set of Channel 4 News. It was here in October 2005, just after the hustings, that presenter Alex Thomson asked the question MPs had avoided. After rehearsing Mr Cameron's usual stance, Thomson said: "If I asked you if you'd snorted cocaine as an MP, you'd therefore say 'No' wouldn't you?" Mr Cameron replied: "That's right, but please, I mean, I think we've dealt with this issue ..."
To which the presenter, showing more persistence than a roomful of backbenchers, said, "So that's 'No?'" Cameron said: "I've absolutely answered your question." Thomson said: "Say no." And Cameron said: "I've just said no."
A C4 insider said yesterday that there was still ill-feeling in the Tory leader's camp towards the programme, but described the MP as "a bad loser". Mr Cameron may consider such interrogation impolite or inappropriate, but if he doesn't confront it soon there is no chance of the question going away.
How Labour will exploit the Bullingdon Club photograph
The Labour Party is planning to use the now iconic photograph of members of the elitist Oxford drinking society, the Bullingdon Club, first printed in last week's 'Independent on Sunday', in future election campaigns.
The party believes the photograph of David Cameron and Boris Johnson posing at Oxford in wing collars will show that the modern Tory party is out of touch with modern Britain.
Labour figures plan to turn the photograph into a poster for May elections with the slogans, New Model Tories, or Are They Really Thinking What We Are Thinking?
One senior Labour source said yesterday: "This poster sums up what Cameron is all about. It shows just how elitist and out of touch with real people he really is."
The exclusive all-male dining society for former public school boys was notorious for heavy drinking and rowdy hi-jinks. The photograph, taken by a local agency in 1987, shows the students wearing royal blue tail coats with ivory lapels that cost around £1,000 each.
Labour figures believe the picture will evoke images of 'Brideshead Revisited' and an antiquated class system.
Labour will have to pay the copyright owners for its use. But some fear that the party's huge debts mean it may not be able to afford to reproduce it on a mass scale.
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