Gordon Brown will welcome Peter Mandelson back into the Labour fold today as he seeks to rally his MPs ahead of what promised to be a bruising Parliamentary session.

Although Mr Brown is to address a meeting of the Parliamentary Labour Party, all eyes will be on Mr Mandelson, now eligible to attend after his surprise recall to the Cabinet.

Mr Mandelson yesterday dismissed as “dirty tricks” reports that he had “dripped pure poison” about Mr Brown. The new Business Secretary said the story came from a dinner he had had with George Osborne, the Shadow Chancellor, in a Greek taverna over the summer.

In a barely-veiled threat to retaliate, he said: “We talked as much about his colleagues and the state of the Tory party, as we did about the Labour party. I would no sooner talk about in public what he said to me about his colleagues than I hope he would what I said about my colleagues, but I can assure you there was no poison being dripped anywhere, either by him or by me.”

He added that he had always been a member of Labour’s “family”. “When times get tough, families pull together and that’s what we are doing.” In an interview with Sky News he said he had taken the job under Mr Brown after Tony Blair told him it was a “no brainer”.

Mr Brown completed his reshuffle yesterday with a shake-up of ministers outside the Cabinet. Among the surprise winners was the Tory defector Quentin Davies who becomes a junior minister at the Ministry of Defence.

It was confirmed that the high-profile job of immigration minister has gone to Phil Woolas, while Vernon Coaker gains promotion within the Home Office to become police minister.

The champion of academy schools, Lord Adonis, makes a surprise move from education to the Department for Transport.

At the Treasury, Stephen Timms replaces Jane Kennedy as Financial Secretary. Ms Kennedy moves to the Environment Department, where she will be Hilary Benn’s deputy. Britain’s first Muslim minister Shahid Malik is promoted to parliamentary under-secretary of state in the Ministry of Justice.

Chris Bryant, Sion Simon and Kevan Jones, who all signed the backbenchers’ letter which prompted Mr Blair to announce a timetable for his resignation in 2006, each gain ministerial office.

Rhondda MP Mr Bryant is deputy Leader of the Commons and Birmingham Erdington’s Mr Simon has a junior post in the Universities Department, while Mr Jones becomes parliamentary under-secretary of state in the Ministry of Defence.

Among those leaving the Government are Kim Howells, the former Foreign Office minister and the energy minister Malcolm Wicks. Mr Brown sought to strengthen his grip on his party bringing back into the whips office the veteran MP John Spellar to serve underneath Nick Brown and Tom McAvoy.

The Prime Minister faces a series of difficult Commons votes this autumn including legislation to increase to 42 days how long terrorist suspects can be detained without charge. The Human Fertilisation and Embryology Bill promises to be another potential flashpoint, particularly if Labour MPs press to include further liberalisation of abortion laws. Other troublesome bills include the Planning Bill, opposed by some Labour MPs for diluting councils’ power to reject controversial developments like nuclear power stations.

There was no job in the reshuffle for leading left-winger Jon Cruddas who turned down a number of offers before finally accepting a Labour Party role. The party was also forced to put out a statement confirming that Douglas Alexander remains as elections co-ordinator after Mr Mandelson denied that he was being lined up for the role.

“I think you’ll find that somebody else is going to be affirmed in that role, somebody I know and trust and admire,” said Mr Mandelson.

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