Alistair Darling and David Miliband are to stay in their jobs as Gordon Brown leaves the top half of his Cabinet intact in a reshuffle today.

Liam Byrne, the Immigration Minister, is tipped to enter the Cabinet after only four years as an MP, the big winner in changes forced by the resignation of Ruth Kelly, the Transport Secretary. But the Cabinet’s “big six” are likely to stay where they are after Mr Brown decided just over two weeks ago to put off a more far-reaching shake-up — intended to be the last before a general election — until the new year.

Apart from the Chancellor and Foreign Secretary, others keeping their present jobs will be Jacqui Smith, the Home Secretary, Jack Straw, the Justice Secretary, Ed Balls, the Education Secretary, and Alan Johnson, the Health Secretary. Mr Brown is widely expected to create a new role of Cabinet enforcer to improve the co-ordination of government departments and ensure that Downing Street’s orders are carried out. And there could be a promotion for Ed Miliband, the Cabinet Office minister and Brown ally, who made an impressive speech at the party conference. Lord Jones of Birmingham, the trade minister, is to stand down, as will Lord Rooker, Labour’s deputy leader in the Lords.

As The Times reported yesterday, Mr Brown will also set up a new Cobra-style economic committee to monitor the financial meltdown and its aftermath. All the key economic ministers will be involved, including the Chancellor, Business Secretary, Work and Pensions Secretary and Environment Secretary.

Those who may have to wait until the new year for Cabinet entry could include Pat McFadden, the Business Minister, and Jon Cruddas, the backbencher who performed well in the deputy leadership contest. Margaret Beckett, the former Foreign Secretary, whom Mr Brown is keen to restore to a central role, could also face a wait.

At one stage during the summer Mr Brown seriously considered a move for Mr Darling. One possibility was to swap him with Mr Miliband and another was to move Mr Balls, his closest ally, to the Treasury.

The need for a wide-ranging shake-up now has lessened as Mr Brown’s position has strengthened during the party conference season, and the sudden worsening of the international financial crisis two weeks ago is said to have convinced him that he should delay bigger changes. Mr Darling is already deeply involved in preparing the Pre-Budget Report, expected early next month, when the full extent of the impact of the financial crunch on Britain will become clear.

Mr Brown and Mr Darling are old friends, a friendship that has remained intact despite obvious tension between Downing Street and the Treasury during the summer. The two have been meeting many times a day as the financial crisis has unfolded.

Lord Jones, the former director-general of the CBI, confirmed that he would be leaving soon. He said that he always intended to do the job for a limited time and it was not a judgment on Mr Brown’s performance.

The appointment of Lord Jones was controversial at the time because he was not a member of the Labour Party. He countered that criticism by saying that the job of promoting trade and investment “should transcend the factionalism of party politics”. He said of his position: “It’s public knowledge that whenever he wanted to reshuffle, he could count me in it and I would slip away. It’s not a comment on him — I think his leadership is very, very good indeed.”

Ms Kelly told Mr Brown in May that she wanted to leave the Government but agreed to stay on until the reshuffle. Controversially, her decision leaked out at the Labour conference last week. That meant that Mr Brown had no alternative but to carry out an early revamp because Ms Kelly would have been derided as a lame duck by the opposition parties on her first appearance in the Commons.

Last night Ms Kelly announced that she would also stand down as MP for Bolton West at the next election.

Mr Brown has held the prospect of a reshuffle over the Cabinet throughout the summer, as his own position has weakened. But a successful keynote speech at the Labour conference and a modest improvement in dismal poll standings have taken the pressure off him, at least for the time being.

At one stage recently it was predicted that next week’s meeting of the parliamentary party could be a bloodbath, but that no longer seems to be the case. Ministers who are known to be unhappy with Mr Brown believe that it would be unwise to move against him during the crisis. Some of them are privately praising the way that he has tackled the problem.

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