Blunkett insists: I was right to downgrade it

"I don't want the children of my Cabinet colleagues or the shadow Cabinet to find that they are treated differently fromthe way their parents were at university," he said.

The Prime Minister is set to back a return of cannabis to class B, amid concerns that downgrading it to class C caused confusion about its legality and fears about the consequences of its excessive use among young people.

Mr Blunkett, who resigned in 2005, defended his downgrading of the drug saying: "There has been a marked fall in cannabis use, which is the result of people being better informed. There has also been the emergence of skunk which is twice as potent as the historic 'weed' so it would be sensible if a reclassification upwards applied to that, which is a very different drug.

"I don't want the police to have to chase those who are foolish enough to break the law by using small amounts of cannabis. I want them to focus on the pushers and the traffickers.

"I understand the politics of sending signals, but I hope we don't throw the baby out with the bath water. The police said my changes would give them the freedom to target class A drugs. I would like them to continue doing that."

Mr Blunkett added a warning about the Government's flagging momentum, saying: "We don't need to be afraid of ideas and we do need to be bold. The Cabinet needs to bed down a bit and gain in self-confidence and the big challenge now is not only to be addressing issues a government can't duck, but to think boldly and radically about the issues of the next 10 years."

Lack of strategic direction has been a criticism of Mr Brown privately voiced by several former Blairite ministers.

After publishing a pamphlet on social mobility this week, Mr Blunkett said: "I'm looking for a refreshed and renewed campaign for Labour here. The Tories and Lib-Dems have been seeking to broaden their appeal by moving onto our territory. We have to get out of an era of politics where having ideas about the future is seen as dangerous."

But he ruled out an attempted ministerial comeback. "I'm not looking for that," he said. "Now I have time to think about ideas without threatening anyone. I'm politically liberated."

Speaking of the "crippling disadvantage" afflicting the poorest families, Mr Blunkett was critical of allowing projects such as Sure Start to dwindle into child-care schemes to allow women to work. "I'm critical that there is a danger of it being watered down," he said.

The former Cabinet minister conceded that families fleeing state schools still pose a problem for Labour's claim to be enhancing social mobility. "It is an issue, especially in London and the South-East," he said. "The challenge is to provide an ethos that is attractive to parents in terms of behaviour, respect and the nonacademic aspects of education as well as the exam results. We need to face it. If 20 per cent of children in inner London go to private schools you can't fail to address it."

Asked if he would insist that his son William by the publisher Kimberly Quinn would be educated in the state sector, Mr Blunkett refused to comment, saying: "I shan't discuss my son. It's private. But my other three children have been educated in the comprehensive schools."

He is understood to have regular contact with the child despite a bitter split from Mrs Quinn. He added: "I am very happy. My quality of life is better than for a long time and my emotional and physical health reflects that."

Asked if he had recovered from what he has referred to as the "terrible trauma" of his doomed relationship, he said simply, "Yes."