Dear Diary: tomorrow I must go to court to stop that ghastly little man ridiculing me

Alan Clark, the notorious womaniser and MP for Kensington and Chelsea, is undoubtedly unique. But it is to be wondered whether the patrician Tory qualifies for protection under the 1988 Designs and Patents Act.

This will be tested tomorrow in the High Court in London when Mr Clark takes on the London Evening Standard and its journalist Peter Bradshaw over "Alan Clark's Secret Political Diary", a spoof account of Mr Clark's life and times which appears in the London evening paper every Thursday.

In the civil courts Mr Clark and his lawyers will charge that the paper is "passing off" the diary as Mr Clark's own work. The column carries a photograph of Mr Clark and his name in the headline, but below that in the introduction each week it makes it clear the diary is being written by the Standard's leader writer Peter Bradshaw.

"Alan has had something of a sense of humour failure about this," said a source close to the Standard. "The fact of the matter is that such diaries have a long satirical history."

It is thought that the newspaper's lawyers will point to examples of similar "fake" diaries going back to Mrs Wilson's Diary in Private Eye in the Sixties and its modern day imitator, Mrs Blair's Diary, in the Observer.

"If he gets away with suing the Standard for passing off it could have terrible consequences for all satirists," said the source. "It would presumably be possible for Tony Blair to sue Rory Bremner for passing himself off as the Prime Minister."

The trial is expected to last three days. Mr Clark's office refused to comment on the case or to say whether Mr Clark would be appearing in court.

Political sources believe that the case is about much more than Mr Clark's desire to prevent newspapers using his image.

The secret diary plays heavily on Mr Clark's reputation as an elderly roue and portrays him as an embattled right-winger of the Thatcherite tradition, railing against any centralising tendencies of the Tory party leadership. Its style is akin to Mr Clark's own best-selling diaries which candidly portrayed his dislike of many members of his own party, his infatuation with Margaret Thatcher's ankles, and numerous other women.

"It is an open secret that Alan wants ermine," said one Westminster source referring to Mr Clark's desire for a peerage. "He wrote his diaries and made his reputation as a maverick when he was out of the House (of Commons) and he didn't think it mattered. Now he's back he wants to be taken more seriously. He tried to become chairman of the 1922 Committee and then deputy chairman. He failed in both and now all that's left is the Lords. He wants the diary stopped because he thinks it will damage his chances."

"However Alan has this conflict," added the source, "between wanting to be grand and patrician, and wanting to be the old rogue, brilliant diarist and brutally frank enemy of hypocrisy. So, at the same time as going for the Standard, he is working on another volume of diaries."