For all his talk of unity, Livingstone still has to prove he's a team player

It wasn't quite Margaret Thatcher's St Francis of Assisi refrain on the steps of Downing Street, but when Ken Livingstone accepted the chains of mayoral office yesterday, he spoke only of unity.

Effective relations with the Government, with Millbank and with the parties on the Greater London Assembly were among his key concerns. Wounds should be healed, not deepened, he stressed.

Yet as Labour's most famous expellee gets stuck into the serious business of governing London this weekend, it is clear that he will have to work hard to prove he has changed the habits of a lifetime. Or, as one minister put it more prosaically in the early hours of yesterday: "Ken and the Government, it's like a dog and a lamppost - he just can't resist."

Scepticism about whether the left-wing leopard has changed its spots has certainly been a key theme of Labour's campaign against Mr Livingstone over the past months. He has been painted variously as an anarchist, a loony tax-and-spender and a chatshow charlie.

Tony Blair himself repeated the mantra that the former GLC leader had to prove that he had changed, that he had ditched the "gesture politics" that left Labour in the political wilderness for nearly two decades.

But now that Mr Livingstone has resumed real power once more - not to mention an annual budget of £3.6 billion and a national platform - the Government is left with a dilemma about how to deal with him.

As the London results trickled in early yesterday and the reality of Mayor Livingstone became apparent, several cabinet ministers appeared to offer an olive branch.

David Blunkett, Margaret Beckett and Jack Straw all stressed that the Government would work constructively with the maverick independent as long as he worked constructively with them.

Mr Blunkett said he believed the MP had "tempered" his radicalism, while Trevor Phillips, the deputy mayoral candidate, said there would be "no vendettas" pursued.

The tone of their remarks was much softer than recent Labour attacks on Mr Livingstone's integrity suggested.

The newly elected Mayor made the most of the softer approach yesterday, pointing out that he had got in touch with ministers within minutes of winning the top job.

"I strongly welcome the various statements made since the mayor election by Government ministers on co-operation with the Mayor. I am already in contact with ministers to coordinate policy between Government and the Mayor on the issues which face the capital," Mr Livingstone said.

A meeting with the Prime Minister, possibly at Chequers this weekend, would confirm the rapprochement between Mr Blair and the man he confidently predicted would be a "disaster" for London.

Given that creating the job of Britain's first directly elected mayor was Mr Blair's own pet project, it is now in Downing Street's interests to make the mayoralty work.

But while Red Ken may have transformed himself into Cuddly Ken over the years, some members of the Government feel the new Citizen Ken is not to be trusted. Gordon Brown, for one, has made clear that he loathes Mr Livingstone, a feeling that appears to be mutual.

The Mayor is desperate to rejoin the party to which he has given most of his adult life. Whether he can resist taking aim at the Government lamppost remains to be seen.