Alistair Darling, Jack Straw and David Miliband are poised to secure “big beast” posts this week when Gordon Brown carries out the biggest Cabinet shakeup since 1997.

Three new women members, including Baroness Scotland of Asthal, who would become the third black Cabinet minister, are expected to be brought into the top team.

Lady Scotland, who is at present a Home Office Minister and is a QC, is being considered for a number of roles, including Attorney-General to succeed Lord Goldsmith.

Yvette Cooper, the Housing Minister, and Beverley Hughes, Minister for Children, are in line to come into the Cabinet for the first time. Jacqui Smith, currently Chief Whip and in the Cabinet, is also tipped for a substantial promotion when Mr Brown unveils his team on Thursday.

Hazel Blears, the Blairite party chairman, whom Mr Brown admires for having stuck to government policy during the deputy leadership contest, will also be promoted now that Harriet Harman has become chairman. Ruth Kelly, the Communities Secretary, will stay in the Cabinet, but probably be shifted.

Several women members are expected to stand down. Hilary Armstrong, the Cabinet Office Minister, has already said she is going; Margaret Beckett, the Foreign Secretary, may depart for a senior backbench post; and Baroness Amos, the Lords leader, could go. Patricia Hewitt, the Health Secretary, is likely to be moved.

Mr Darling, the Trade and Industry Secretary, is now expected to replace Mr Brown as Chancellor.

Mr Straw is also in line for one of the biggest jobs in the Cabinet, taking charge of Mr Brown’s programme of constitutional reform and the Justice Ministry, and possibly with the title of Lord Chancellor, the first time it would have been used for a Commons minister.

Mr Straw could become Deputy Prime Minister if Mr Brown decides to have one. Geoff Hoon, the Europe Minister, is expected to return to the Cabinet, possibly as Chief Whip.

Mr Miliband is set to take charge of a beefed-up Environment Department or possibly become Foreign Secretary. Alan Johnson, who failed to become deputy leader, could remain Education Secretary or even become Home Secretary.

Other vacancies have been caused by John Reid’s decision to stand down and Mr Brown’s move to No 10. Ed Balls, Mr Blair’s long-time adviser and husband of Ms Cooper, will enter the Cabinet, and there are expectations that Andy Burn-ham, the Health Minister, and James Purnell, the Pensions Minister, will join them.

Jon Cruddas, whose performance during the deputy campaign was also rated highly by the Chancellor even before he came third, is in line for an important party post, sources have told The Times. Mr Brown will ask him to continue to work on party reform.

— Douglas Alexander, whom Gordon Brown has tasked to win the next election, is one of his closest personal and political friends. He helped to coordinate Labour’s 2001 landslide winning campaign and will be responsible for having the party machine ready whenever Mr Brown decides the time is right to win an election.

The 39-year-old Scot entered Parliament as MP for Paisley South in 1997. He served as Minister for Trade and as a Cabinet Office minister, before joining the Cabinet as Europe Minister after the 2005 election.

He has been Transport Secretary and Scottish Secretary since May last year.

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