It will either be a great publishing success, or the best earner for the legal profession in decades. Either way, Tom Bower's new book is going to generate plenty of headlines.

The investigative author, whose past 'victims' have included Harrods owner Mohamed al-Fayed, Mirror fraudster Robert Maxwell, and even Chancellor Gordon Brown, is taking on one of his toughest subjects yet: the unauthorised biography of former pornographer and Express newspaper group owner Richard Desmond.

The book - previously rumoured to be work in progress, but confirmed by Bower yesterday - will be all the more controversial because of Bower's connections with Desmond's bitter enemy, the Associated Newspapers group run by Lord Rothermere.

Bower's wife is Veronica Wadley, editor of Associated's London title, the Evening Standard , while Bower has been a regular writer for Associated's flagship Daily Mail .

'I'm writing it, and that's that,' the author said. Asked if he thought the book would be regarded by Desmond as an escalation of the bitter feud between the two newspaper houses, he said: 'I've nothing more to say about it.'

People close to Associated, though, believe the book is close to being finished, and have slotted in publication for later this year. 'They [Associated] think it's coming out soon, and are very pleased,' said one media expert.

Another said: 'I think it's almost ready for publication. But I don't think you should automatically assume it will be serialised in the Daily Mail .' Bower has agreed serialisation deals with newspaper groups, including Associated, in the past.

It is not known whether Associated has made available to Bower any of the information it has accumulated on Desmond during its war of words with the Express boss. Desmond was recently linked to a trial involving New York mafia members.

Bower also declined to say whether he had been in contact with Desmond, as has been rumoured recently, although he is known to be painstaking in the research he carries out prior to publication.