Can Mr Campbell turn his jottings into a pension?

After the world was given a glimpse of Alastair Campbell's private diaries at the Hutton inquiry last week, an ambitious literary agent wrote to the Prime Minister's director of communications offering his services. But Giles Gordon got a curt reply. "Dear Mr Gordon, It won't surprise you to know I've no need of a literary agent. Yours sincerely, Alastair Campbell."

A lethal mixture of humour and contempt, the letter was typical Campbell. It suggested that Tony Blair's right-hand man had no intention of publishing his memoirs. But it also pointed to an obvious fact: he would have little trouble persuading a publisher to take on what could be the best insight into the New Labour phenomenon.

Mr Campbell has certainly made no secret of the fact that he was keeping a first-hand account of the highs and lows of the Blair era. Soon after Labour swept to power in 1997, he told the novelist and Labour supporter Robert Harris: "I'm going to make more money out of my diaries than you've made out of all your books." Given that the novelist made £1.8m on the American rights to his book Fatherland, the boast was a large one.

Despite his £110,000 salary, Mr Campbell and his partner are not wealthy and he has often referred to his private penned thoughts as his "pension".

Various prices have been put on the Campbell diaries, ranging from £1m to £5m, and there is no doubt he could make a lot from the newspaper serialisation of his memoirs, possibly more than £500,000 for long extracts. A publisher could offer a further £1m, a record for a political book.

The Hutton inquiry whetted the appetite of publishers and the public, offering a tantalising insight into the late-night jottings and cabinet table note-takings Mr Campbell has made over the years. When he read from his journal in court 73 last week, he triggered laughter by declaring that it was "not intended for publication".

He said that although he did not keep a nightly record, he wrote down his thoughts every few days. Among the entries were eye-catching phrases. He described the row between the BBC and Downing Street as a "firestorm" engulfing the Government. On 1 June, he wrote that the situation was now "grim ... grim for me, grim for TB and there's this huge stuff about trust".

But it is unlikely the Campbell diaries will be critical of Mr Blair. They will instead be pored over for observations about Gordon Brown, the Chancellor, and other ministers, and Mr Campbell's central role liaising with the Bush White House in the Iraq conflict. Mr Campbell has said he will "need a libel lawyer for every page".

One unexpected admirer of the Campbell diaries has been Robin Cook, the former Foreign Secretary who denied he was forced to choose between his wife and his mistress by Mr Campbell in August 1997. "Like a lot of people, I do hope he will yet be publishing those diaries," he said.

Many predict Mr Campbell will hand over the diaries to his close friend Gail Rebuck. Ms Rebuck is chief executive of Random House, the biggest- selling book publisher in Britain, and the wife of Philip Gould, Downing Street's polling strategist. This month, the Goulds were on holiday with Mr Campbell and his partner, Fiona Millar in France. With friends like that, who needs a literary agent?