Some will suggest that the decision, one that is likely to be popular with the public, is to get Gordon Brown out of a hole following last week's election results. That is unfair. He announced last July his intention to review previous decisions.

The whole muddle could have been avoided. The longer the uncertainty, the greater the confusion for the public, young people, parents, teachers and the police. That confusion and chaos can be tracked to the stubbornness of David Blunkett when the then Home Secretary announced plans in October 2001 to reclassify the drug to Class C when giving evidence to the Home Affairs Select Committee.

It was a complete U-turn and was received with shock by those working operationally in drug enforcement, education and treatment. I gave evidence to the Home Affairs Select Committee some days after Mr Blunkett and, in doing so, highlighted the concerns of headteachers, youth workers and many others about the mixed messages that reclassification would send out.

I referred to the many deaths that I had reviewed of young drug users who commenced their drug career on cannabis, despite this gateway theory being constantly challenged by academics.

Also giving evidence was Brian Paddick who was Brixton's police commander at the time. More recently, he was the Liberal Democrats' mayoral candidate in London.

It was his "softly, softly" experiment in Brixton on cannabis that so influenced Blunkett. Our views differed significantly and members of the committee, including a young David Cameron, closely questioned us. Interestingly, Mr Cameron did not detract from the conclusions of the committee months later in its final report which recommended not only changes for cannabis, but also for ecstasy. David Blunkett's immediate successor, Charles Clarke, attempted to rectify the position in January 2006 but was thwarted by the Advisory Council on the Misuse of Drugs whose members were never likely to change the views that they had expressed in 2002.

After asking the Advisory Council again to review the classification of cannabis, the Prime Minister and Home Secretary cannot be surprised that they came back recommending no change.

It left the Government with no alternative other than to ignore that advice and seek Parliamentary approval to return cannabis to its former Class B status.

Many will argue that cannabis use by young people has dropped. That may be the case – but it probably has more to do with social trends, and other activities by young people, rather than the lower classification over the past four years.

What is very clear is that the consequences are very serious for the many young people who take the drug in the form of the more powerful "skunk" variety, particularly with regard to their mental health, learning, sport, physical activity and longer-term employment prospects.

The number of cases of young people harming themselves, or committing terrible crimes of violence through mental illness made worse by cannabis use, has increased over the past four years. The evidence linking cannabis to psychiatric illness has continues to mount. The market has gown considerably, as witnessed by the discovery of hundreds of cannabis farms in the UK.

The planned reclassification also poses issues for the police service. The service is used to policy U-turns and will respond positively, albeit at a time when its resources are already stretched.

Enforcement in relation to possession of cannabis will quite rightly follow, but the opportunity for discretion should remain. A power of arrest for possession has always been in place. Until now, the presumption has been not to use this power. That will have to be reviewed.

Members of the Advisory Council on the Misuse of Drugs will feel aggrieved that all their recommendations have not been accepted. They should not be.

Never again should confusion be allowed to occur on the whim of a single Cabinet minister. While the return of cannabis to Class B status must go ahead, and quickly, there is an opportunity to review the whole classification system and membership of the Advisory Committee. There are too many members. It should be reduced in size, but with greater links to the regions where real evidence of harm can be gathered.

The Government's own Select Committee on the use of scientific evidence reported two years ago that policy and law should reflect the science, but additionally the harm which drugs can cause to individuals and communities.

If this had been the case in recent years, there may have been a case for milder cannabis to have a lower classification than the stronger skunk variety.

The move by the Government is to be welcomed, despite its lateness. Anti-drug work now requires a sharper focus through Crime and Disorder Partnerships. It is not difficult. Be clear about harm, educate the young, target the suppliers, treat the addicted and restore clarity.

Geoff Ogden was head of Humberside CID before becoming the drug action team manager for Hull and the East Riding.

Read the case against reclassification>>