Mandelson returns in Cabinet change

The Cabinet changes, which also saw John Hutton installed as Defence Secretary and Margaret Beckett return to the frontbenches as housing minister, left a few gaps in the junior ministerial ranks - including immigration minister and police minister - which are expected to be filled by Mr Brown within the next few days.

David Cameron also looks likely to be forced into his own reshuffle to take account of changes to the machinery of government introduced by Mr Brown, including the creation of a new Department for Energy and Climate Change, headed by Ed Miliband.

It had been thought that Mr Cameron would prefer to hold back a revamp of his frontbench team until the Parliamentary Standards Commissioner has completed an inquiry into allegations that Tory chairman Caroline Spelman wrongly paid a nanny from allowances intended to pay for her parliamentary staff.

As the final details of Mr Brown's reshuffle emerge, attention will be focused on whether he has found a place for darling of the left Jon Cruddas, who has been tipped for a Government job since his well-regarded campaign for the deputy leadership last year.

Reports suggest that Mr Brown has spoken with Mr Cruddas, but that the Dagenham MP indicated he would prefer to retain the liberty of remaining outside Government.

Mr Mandelson's appointment was seen as an olive branch to Blairites who were stung by Mr Brown's perceived put-down of their favourite David Miliband as a "novice".

However the appointment came with risks attached. Critics see him as a divisive figure, best known for his plotting and manoeuvring to undermine rivals within the Government and his mastery of the dark art of political spin.

Mr Brown said that bringing the EU Trade Commissioner and others into his Cabinet meant he had "serious people doing serious jobs in serious times", while Mr Mandelson himself joked that it was a case of "third time lucky".

The former Hartlepool MP will be made a peer so that he can answer parliamentary questions in the House of Lords, having given up his seat in the Commons when he became Britain's European Commissioner in 2004.