Trying to extrapolate a liberal drug policy from David Cameron is like punching fog: a gargantuan effort for no reward whatsoever.

There is more chance of the Prime Minister running naked through Downing Street with ‘big society’ tattooed on his chest than there is of him easing up on drug classification.

A relaxed policy is an instant turn-off for his core electorate and unlikely to win him many votes from the left.

Hence, it’s a no-go.

Drugs law policy will always ultimately be decided by instinct.

Suggest a relaxation of the rules and the media will simply wheel out a grieving parent of a teenager who has died after taking an ecstasy pill.

Put forward a programme to offer heroin addicts a structured but expensive course of drug rehabilitation and the mob will have you out of power before you know it.

Rationality will forever be trumped by emotions, no matter how illogical and counter-productive current laws seem.

All of which suggests the latest effort to decriminalise drugs in the form of a letter to the PM may be yet more whistling in the wind.

Signatories such as Sir Richard Branson and Dame Judi Dench appeal for a rehash (you have to love that punnery) of the current laws, arguing they do little to prevent thousands of people using drugs and being burdened with a criminal record when they are caught.

‘In the last year alone nearly 80,000 people in the UK were found guilty or cautioned for possession of an illegal drug – most were young, black or poor,’ says the letter.

‘This policy is costly for taxpayers and damaging for communities.

'Criminalising people who use drugs leads them to greater social exclusion and isolation, making it much more difficult for them to gain employment and to play a productive role in society.’

This argument has been made many times before, not least by senior members of the legal profession, and more are included here, including several barristers and solicitors.

They sit slightly incongruously alongside Guardian columnists and luvvie actors, and are a reminder that while legal practitioners are required to uphold the law, they might not always agree with it.

They deserve credit for sticking their heads above the parapet, in spite of whether you agree with their views.

They won’t win this argument, but they’ve helped to thrust this important issue back into the news agenda.

One thing’s for sure, it won’t go away anytime soon.