Home secretary Jacqui Smith – a woman who has confessed to using cannabis as a student – has today confirmed that cannabis is to be reclassified as a class B drug.

The decision has been welcomed by the Conservative Party. As we know, Tory leader David Cameron was at the age of 15 confined to the grounds of Eton College for two weeks after being caught with a joint.

It comes just days after the election of Boris Johnson – a man who admits smoking ‘quite a few spliffs’ as a schoolboy and finding them ‘jolly nice’ – was elected mayor of London.

Former chancellor Norman Lamont has incredibly enough confessed to eating space cakes, while Alistair Darling, the man currently in charge of the Treasury, also knows what to do with three Rizlas and a ripped up cigarette packet.

Under the law as it stood at the time of these people’s youthful experimentation, and as it will now be again, all of them could theoretically have been sent to prison for five years for simple possession.

True, custodial sentences are rarely dealt out to young people nicked with a bag of grass about their person. But as ever with law and order issues, there is a class dimension to how the punishment operates.

When I was a working class teenager in the 1970s, my friends were regularly fined the equivalent of two to three weeks’ wages if the Old Bill found them in possession of small quantities of dope. That constitutes retribution qualitatively more severe than being ‘gated’ for a fortnight at Britain’s top public school.

Today, a caution is by far the most likely outcome in such cases. But as the Metropolitan Police’s own research discovered two years ago, in instances where charges are pressed, black people are disproportionately likely to find themselves in the dock.

In the view of experts such as the Advisory Council on the Misuse of Drugs, there is no strong case for reclassification. What is more, with dozens of MPs of all persuasions on record as having used cannabis in the past, it can have little credibility with the public.

This is, in other words, New Labour gesture politics of a potency on a par with such legendary seventies marijuana variants as Thai Stick. In practical terms, reclassification will have no effect whatsoever.

The only proffered justification – advanced by the prime minister a few weeks back – is that it ‘sends a message’ to young people that cannabis use is ‘unacceptable’.

Teenagers, who rarely hold anyone over 40 in particularly high regard anyway, will draw a ‘message’ from this pronouncement, alright. But I suspect it will not be the one for which Gordon Brown is hoping.

Their rather more likely conclusion will be that middle aged white politicos who preach the virtues of doubling already hefty prison sentences for offences they themselves committed 20 or 30 years ago are a bunch of hypocritical old farts. In this, the youth of today might not be far wrong.