Her sudden departure, a day before other MPs leave for their long summer break, strengthened signals that she is to remain at the Northern Ireland Office, and there were hints from No 10 that she will stay in the Cabinet.
Downing Street was playing down the significance of her departure. "She has a perfect right to go on holiday," said a spokesman. "Ministers are encouraged to spread their holidays over the summer."
Mr Blair wanted to move Ms Mowlam after David Trimble, the Ulster Unionist leader, said she had lost touch with the loyalist community, but she made it clear last week in an extraordinary move that she wanted to stay in the Ulster post.
Ms Mowlam's early departure underlined her need for a break after the exhausting talks which failed to produce an agreement for the devolution of powers to Ulster. She is still recovering from treatment for a brain tumour.
With the Northern Ireland peace talks "parked" for the summer, the SDLP leader, John Hume, last night called on Mr Blair to avoid imposing any fresh timetable on the former US senator George Mitchell, who has been brought in to find a way through the impasse over the refusal of Unionists to sit with Sinn Fein in a power- sharing executive until the IRA has begun decommissioning its weapons.