Decriminalising cannabis may be an issue the Government does not want aired in the Commons, but it is to be discussed at Westminster - and Independent on Sunday readers will have the opportunity to take part. The debate, which the Government is reluctant to stage, is being organised by the IoS at the nearby Queen Elizabeth II Conference Centre as part of our campaign for decriminalisation. It will be sponsored personally by Richard Branson and the Body Shop, headed by Anita Roddick.

"We need a debate on cannabis, so the Body Shop is happy to sponsor this one," said Ms Roddick.

The forum, which will take the form of a one day conference, will be chaired by Channel 4 news presenter Jon Snow. A panel of speakers representing each side of the argument will address the meeting followed by an open forum with questions from the floor in the style of BBC's Question Time.

Speaking for decriminalisation for recreational and medical use will be Colin Blakemore FRS, the Waynflete Professor of Physiology at Oxford University and President of the British Neuroscience Association, and Ron Clarke, a former senior officer with the Greater Manchester Drugs Squad.

Ms Roddick will speak about the need to make cannabis more easily available for those with a medical need. Colin Phillips, Project Director for the Prince's Trust and a representative on the Runciman Inquiry into drug law reform, will also attend.

The case against decriminalisation will be put by a senior Home Office official, a leading police officer and prominent anti-addiction campaigner. The Government's drug policy co-ordinator, "the drugs Tsar" Keith Hellawell will also be invited, along with MPs from all parties.

Attendance at the conference, which is to be held on Thursday 11 December, is by invitation only, and 400 seats have been reserved for IoS readers. To apply for a seat fill in the coupon above.

Meanwhile, other developments this week include:

! Two reports into Britain's drug culture warning the Government to abandon the stereotypical image of drug users as anti-social drop-outs. An EU drug monitoring group revealed that Britain is Europe's biggest market for cannabis (13 per cent of our citizens admitted to having used the drug in the last year). The Demos think-tank reported that most young drug-takers lead independent lives and respect their families in much the same way as their non-drug taking contemporaries.

! On Thursday night, BBC Question Time's studio audience vote came out on the side of legalising cannabis, with 55 per cent saying they would be in favour.

! On Friday, the Express announced the appointment of a new Drugs Correspondent. "We are in favour of a very open debate and the new correspondent will help us formulate our policy on this as well as covering stories," said Mr Richard Addis, the editor.

! The Liberal Democrat Youth Movement pledged its support to the campaign, in defiance of the official party line which calls for a Royal Commission on drugs.