Exit the spinmeister

Alastair Campbell bowed to the inevitable yesterday when he said he would stand down as Downing Street's director of communications and strategy within four weeks.

Although the eventual departure of Tony Blair's closest aide had been widely expected, Mr Campbell surprised Westminster by announcing his intentions midway through the Hutton inquiry into the death of the scientist Dr David Kelly.

Mr Campbell insisted he had been planning to leave No 10 for a year. But his exit became inevitable after the apparent suicide of Dr Kelly, who was caught in the crossfire of a battle between Mr Campbell and the BBC over the allegation that Downing Street "sexed up" the dossier on Iraqi weapons. Dr Kelly's death has provoked Mr Blair's biggest crisis since he became Prime Minister and he hopes Mr Campbell's announcement will enable him to "move on" by drawing a line under the era of "spin".

Downing Street said Mr Campbell would be succeeded by David Hill, a former Labour director of communications who is a director of Bell Pottinger Good Relations. No 10 said Mr Hill "will operate within a new structure" to be announced next week. The changes are expected to curb the power of political aides.

Mr Campbell said his departure had nothing to do with the Hutton inquiry. He wanted to "get a life back for me and my family" after working for Mr Blair since 1994. Mr Campbell's partner and mother of their three children, Fiona Millar - who works for Cherie Blair - will leave Downing Street at the same time. Mr Campbell and his partner have been alarmed by the influence over Mrs Blair held by Carole Caplin, her controversial lifestyle guru.

Mr Campbell said: "It has been an enormous privilege to work so closely in opposition and in government for someone I believe history will judge as a great transforming prime minister." While there were "huge upsides" to his job, there were also "huge downsides", he said. "The pressures are real and intense, but in doing the job you learn to live with them. It is your family that pays a price." He said he wanted to write about politics and sport, broadcast and give speeches.

He did not want to become an MP and said any books, including his potentially explosive diaries, were "some time off". Mr Blair, whose "inner circle" of close advisers has shrunk since he came to power, said Mr Campbell was "an immensely able, fearless, loyal servant of the cause he believes in, who was dedicated not only to that cause but to his country ... He was, is, and will remain a good friend."

It is believed Mr Campbell initially intended to depart after the Hutton inquiry reported because he wanted, if possible, to clear his name before quitting. But Lord Hutton will not report until October and, after giving evidence to the inquiry last week, Mr Campbell was anxious to leave as soon as possible. Friends say he had lost his appetite for his job and was keen for his successor to take over before Mr Blair launches a political fightback at the Labour Party conference in Bournemouth in four weeks.

Mr Campbell, who promised full co-operation with the inquiry, could be summoned back to answer further questions on his role in the naming of Dr Kelly when the inquiry reaches its second phase.

Some MPs believe his exit may be partly designed to limit the damage to the Government if he is criticised by Lord Hutton's report or endures a difficult cross-examination.

Menzies Campbell, the deputy leader of the Liberal Democrats, said the timing "could hardly be more surprising" because Mr Campbell's role was still a "live issue"at the inquiry. He said the move gave Mr Blair a chance for a "fresh start", but added: "It should not divert us from the central question of whether Britain went to war on a flawed prospectus, either because of inadequate intelligence, or the mishandling of intelligence once it had been obtained."

Theresa May, Conservative Party chairman, said Mr Campbell's departure "will not mean an end to the culture of spin and deceit at the heart of Government''. Mr Campbell had been sacrificed because his position had become untenable after the Kelly affair.