Price, a former BBC reporter who is a close friend of Peter Mandelson, worked in No 10 from 1998 to 2001. He claims that the media was bullied, browbeaten and bribed with favours to report Labour favourably and that the BBC reveals its questions in advance to Blair at press conferences in return for their reporters being chosen to ask their questions first.

Price claims that the cabinet was often reduced to the role of bystanders as Blair and his spin doctors made the big decisions.

Under civil service rules Price, 47, was obliged to submit his manuscript for government clearance, but some of his uncensored extracts are published today in The Mail on Sunday.

When Blair first sent forces into Iraq, when Britain and the US launched airstrikes in December 1998, Price records in one entry: “I couldn’t help feeling TB was rather relishing his first blooding as PM, sending the boys into action. Despite all the stuff about taking action ‘with a heavy heart’, I think he feels it is part of his coming of age as a leader.”

Another entry, later changed at Downing Street’s instigation, reveals that Blair erupted in fury when Labour was doing badly in the first elections to the Welsh Assembly in 1999, shouting “F****** Welsh”.

At other times Campbell’s influence over the prime minister reads like a satire, with the spin doctor calling Blair a “dickhead” to his face and the two men keeping a score-sheet to see who could get the most soundbites from a speech on the television news.

Price also claims that the Anglican prime minister was anxious to stop his flirtation with his wife’s Catholicism leaking out. While holidaying as the guest of Prince Girolamo Strozzi in Tuscany, he prevented his host from videoing him taking holy communion.

The diary also claims two Labour officials had sex on a sofa in Blair’s office in Labour’s Millbank HQ as cabinet ministers celebrated their second election landslide victory yards away in 2001.

Blair also admitted in one discussion “almost wistfully” that private schools “give kids a much better education”, despite being publicly committed to the state sector. And he “alarmed” aides by calling for a “dramatic change” in the NHS, including privatising parts of it.

Price also refers to Blair’s “vanity factor”. When the prime minister was nervous of being seen in public wearing glasses for the first time, he devised a “glasses strategy”, which involved arranging for a friendly journalist to spot them accidentally on his desk. Blair wanted designer frames, but Campbell told him to stick with NHS glasses.