Hewitt quits as Health Secretary

In a letter to the new Prime Minister, Ms Hewitt said she had decided to step down from Government so she could give more time to her "constituency and family".

Although Mr Brown had offered to keep her in the Cabinet she felt it was the "right moment" to go. Mr Brown thanked Ms Hewitt for her "outstanding contribution" to the Government.

Ms Hewitt wrote: "When we met last month, I explained that I had decided, for personal reasons, to stand down from government. While I very much appreciate your offer for me to remain in Cabinet, I feel that this is the right moment for me to give more time to my constituency and my family - something my family would say is long overdue!"

Mr Brown said that Ms Hewitt could be "justly proud" of her achievements, particularly at the Department of Health and in her former role as Trade Secretary.

She has agreed to chair a "manifesto committee" to develop the party's policy on Europe.

News of the departure came after it was confirmed Baroness Amos was leaving the Government.

Mr Brown has proposed the peer, formerly Leader of the Lords, to become the EU's Special Representative to the African Union.

At least three top Cabinet jobs now need to be filled in the reshuffle, with John Reid having already stood down as Home Secretary and Mr Brown vacating the Treasury.

Foreign Secretary Margaret Beckett is also expected to be replaced, as is Justice Secretary Lord Falconer.