HENLEY MP Boris Johnson left fellow MPs, including his Tory leader David Cameron, in a spin this week after confessing to snorting cocaine while at university.

Mr Johnson said he tried the Class-A drug, but it had no effect on him, and that he had often smoked cannabis - tearing up Mr Cameron's carefully crafted rulebook on dealing with youthful narcotics indiscretions.

Asked about cocaine, Mr Johnson told GQ magazine: "I tried it at university and I remember it vividly.

"And it achieved no pharmacological, psychotropic or any other effect on me whatsoever."

Mr Johnson had previously said, on TV show Have I Got News For You, that he was once given cocaine, but sneezed, "so it did not go up my nose".

In the GQ interview, asked by former Daily Mirror editor Piers Morgan whether some of the powder crept into his nose, "despite the sneeze", Mr Johnson replied: "It must have done, yes, but it didn't do much for me, I can tell you."

Asked if he had tried any other drugs, Mr Johnson responded: "Cannabis, you mean? Yes, I have. There was a period before university when I had quite a few spliffs. But, funnily enough, not much at university. It was jolly nice.

"But, apparently, it is very different these days. Much stronger. I've become very illiberal about it. I don't want my kids to take drugs."

Asked if David Cameron would follow Mr Johnson's lead, the Tory leader's spokesman said: "We have nothing further to add. It's exactly as it was. No comment on his life before going into politics."

Other county MPs Ed Vaizey, at Wantage, and Andrew Smith, the Oxford East MP, both refused to follow Mr Johnson's lead. Tory Mr Vaizey, who attended Oxford University around the same time as Mr Cameron, joined his leader in saying "no comment" to the drugs question. Labour MP Mr Smith also said: "I have always and consistently declined to comment on this."

However, Dr Evan Harris, MP for Oxford West and Abingdon, said he had never tried either drug.

Dr Harris said: "I didn't take cocaine or cannabis, but the question for Conservative Party politicians is why their policy is to give criminal records to all young people who experiment with these drugs while either having done it themselves or even worse, in the case of David Cameron, refusing to give a straight answer.

"Liberal Democrats believe that we should be criminalising the dealers and the pushers.

"Tory policy, trying to appear tough on drug-taking, does not permit a defence of youthful indiscretion, so Boris Johnson really has to explain why he is not seeking to prosecute himself to the full extent of the law that he wishes to impose on everyone else."

Banbury MP Tony Baldry was abroad on parliamentary business and could not be contacted.

Ann Ducker, president of South Oxfordshire Conservative Association and leader of South Oxfordshire District Council, dismissed Mr Johnson's admission with a laugh.

She said: "It was all a long time ago and he is very much against drugs now. We will certainly not be asking for his resignation or anything like that."

But anti-drugs campaigner Anna Nichols, from Didcot, who is running courses on how to 'drug-proof' children, was not happy about it.

She said: "Yet another high-profile person admitting to using drugs points again to the fact that so many across all walks of life experiment with illegal drugs.

"Boris and his family were fortunate that it did not progress beyond experimentation."