It was the type of story that, 18 months ago, as David Cameron was preparing his uphill run for the Tory leadership, might have derailed him. But no more.  Cameron was yesterday privately telling friends that his involvement in a drugs scandal at Eton as a teenager had been something of a 'wake-up call'.  None the less, in public he was quick to direct his officials to issue a different message: an unwavering, unequivocal 'no comment'.  'David felt, and feels, politicians are entitled to a past before they came into politics. He had a past, and he's not going to be talking about it,' a spokesman said.  There seemed two main reasons for the confidence with which Conservative Central Office turned aside questions about Cameron's cannabis smoking at Eton.  The first was that an earlier refusal to be drawn on drugs questions - forged in the heat of the leadership campaign after it came up in a public interview with The Observer's Andrew Rawnsley - had, quite simply, worked. Cameron's strategy team remains convinced his calm yet firm refusal to say anything about drugs when challenged a few days later on BBC's Question Time - and the applause he got from the audience - marked a turning-point in his bid for the Tory crown.  And times, too, have changed. Gone are the days when a politician's brush with any kind of drug necessarily risked serious, even fatal, career damage.  To judge by the initial response on Cameron's weblog last night, many people seem ready to give him the benefit of the doubt on the drugs issue. 'I don't have a problem as long as he is not hypocritical,' said one participant. Another added: 'People can change their opinions over time as they gain more experience...MPs are definitely entitled to a past.'  But in Britain, very few senior politicians apart from Cameron - and, significantly, Tony Blair - now take refuge in a simple 'no comment'.  Some others clearly seem torn between transparency and a sense of embarrassment, and respond with their own acrobatic equivalents of Bill Clinton's famous admission that, while he had smoked cannabis, he 'didn't inhale'.  Even in the US, there have been signs of change. A spokesman for Illinois Senator Barack Obama, who yesterday formally threw his hat into the ring as a presidential candidate, recently defended Obama's admission that he had taken cocaine years before. 'I believe what this country is looking for is someone who is open, honest and candid' about such issues, the spokesman said.  A turning-point on this side of Atlantic came in 2000, during one of the periodic bouts of internal bloodletting among the pre-Cameron Tories.  When Ann Widdecombe, a shadow minister, unveiled plans for a hard-line shift on drugs, party reformers responded with a series of admissions by top Tories that they had dabbled in drugs. Seven of then-leader William Hague's shadow ministers came clean.  They ranged from the current party chairman Francis Maude to senior Cameron policy adviser Oliver Letwin, who memorably declared he had smoked pot by accident. 'At Cambridge, I was a very pretentious student,' he said. 'I grew a beard and took up a pipe. On one occasion some friends put some dope in a pipe I was smoking. It had absolutely no effect on me at all. I don't inhale pipes.'  The current Tory education spokesman, David Willetts, was quoted as saying: 'I had two puffs. I didn't like it and I have never had any experience of drugs since then.'  The closest thing to a Labour 'come-clean' moment followed speculation in a 2004 biography of Blair that he was likely to have had at least a puff or two at Oxford. Only three prominent Labour figures - the late Mo Mowlam, Health Minister Caroline Flint and Housing Minister Yvette Cooper - had admitted having used drugs. Charles Clarke later said he had smoked pot -'once.'  But Chancellor Gordon Brown said, through a spokesman, that he had 'never touched illegal substances'. Also denying drug use were John Reid, Peter Hain, David Blunkett and Jack Straw - despite Straw's having had to deal with a crisis after his son Will offered to sell drugs to an undercover reporter.  One comment during the storm over drugs use surely now haunts its author - Charles Kennedy, the former Liberal Democrat leader, who was forced out of office last year over an undeclared drink problem. Urging both Blair and then Tory leader Michael Howard to answer the drugs question, he said: 'I have never taken drugs. I think it is important that other party leaders come clear on an issue of such huge national importance.'  Cameron's aides last night said he was 'relaxed' about the revelations concerning his teenage drug use. They rejected suggestions that his refusal to comment on whether he might have taken harder drugs at Oxford meant he could have something further to hide.  The added that his broader view on drugs policy remained unchanged. Since standing for the leadership, he has stressed the need to improve drugs education. On classification of individual drugs he has argued for an 'evidence-based' policy and was a member of the Commons Home Affairs Select Committee that issued a 2002 report recommending a major policy review.  Last month, he also said he would be 'relaxed' about legalising cannabis for medicinal use if evidence showed it helped. But the open question last night, some aides acknowledged, was whether the news of his own drugs use might make it more difficult to advocate any liberalisation of drugs policies.  From 1940 used the barbiturate, quinalbarbitone. After his stroke in 1953 he was given amphetamine.  Private papers disclosed that at the height of the Suez crisis in 1956, Eden was on drinamyl, better known as 'purple hearts.'  In March 1992 admitted drug use while a student at Oxford: 'When I was in England, I experimented with marijuana. I didn't inhale and I never tried it again.'  His 1995 memoir, Dreams From my Father, detailed his drug and alcohol use in his high school and college years. He admitted using 'pot...and booze; maybe a little blow when you could afford it.'  In 2000 admitted she smoked cannabis as a student at Durham. She said 'Unlike President Clinton I did inhale.'  Responding to an Oxford contemporary who said Johnson had never taken drugs, the Tory MP for Henley said: 'This is an outrageous slur...of course I've taken drugs.'
Ten years ago a story about drug-taking could have ruined the career of a Tory leader, but now the climate has changed.