Marilyn Monroe and Laurence Olivier were screen legends and details of their one joint venture, the strife-torn and yet delightful The Prince and the Showgirl, always make good reading, writes Peter Unsworth.

And what better than to have it written by someone who was Olivier's assistant and who, because of his youth and innocence, struck up a rapport with Monroe at a time when she was driving his elders and her betters up the wall. The Prince, the Showgirl and Me, by Colin Clark, told the inside story of the relationship between the star and the love goddess. Good reading it was.

But how do you improve on the excellent and the actual? Only by an injection of the brilliant and the highly improbable.

He gives us a charming picture of nine days with Marilyn, days when she needed someone young and caring to lean on.

Yet if the story had got out he would have hit the front pages of the tabloids with even more impact than his more notorious brother - MP, adventurer and philanderer Alan Clark - could ever have dreamed of.

Skinny dipping in the Thames, a visit to Windsor Castle to see his godfather, smuggling herself out under a blanket in a car, sharing a bed (and only a bed!) with a woman still on her honeymoon. It was amazing stuff. Colin Clark, an Oxford graduate, chose not to record the happenings of the nine days until now. He does not elaborate on why he has decided to go into print. Cynics might suggest it is a means to boost the major book (although at 14.99 it is a pricey boost), particularly as he says he could never have written it during Monroe's lifetime. He has had 38 years to think about it. Why now? And how come the narrative is so vivid, the quotes so clear and precise?

How much is fact and how much is fiction only the author can say. The Prince and the Showgirl, like so many others in the story, are no longer around to argue.

To Clark's credit there is nothing sordid in his story. It is warm, endearing and a delightful reminder of someone who is still a star in the hearts of everyone who loves the cinema.