As part of the Gordon Brown's cabinet reshuffle Mr Johnson has been moved into the role, but the Prime Minister has kept Alistair Darling in his job as chancellor along with Jack Straw who will also stay in his role as justice secretary.

The Prime Minister suffered a fourth resignation from his Cabinet in just four days as Defence Secretary John Hutton followed James Purnell in stepping down.

But unlike the Work and Pensions Secretary, Mr Hutton did not criticise Mr Brown's leadership as he went and sources stressed he was departing for "family reasons".

David Miliband will remain at the Foreign Office. Chancellor Alistair Darling has also fended off efforts to shift him from Number 11 - despite speculation that Mr Brown had wanted to install his close ally Ed Balls.

The developments came amid signs that Labour had performed badly in Thursday's local elections, although the full picture will not become clear until later on Friday.