Why did you not conquer Monroe?

We have just received a copy of your book. Deliveries are not so prompt here and we have to cope with the censors. Please don't ask whether I am in Heaven or Hell. All I will say is everyone acts so sweetly and properly that while it might be Heaven to some, it sure as Hell isn't to me.

It is on the question of proper behaviour I wish to address you. My Week With Marilyn is your missing chapter, the section of the otherwise meritorious book, The Prince and the Showgirl and Me, a much sought-after account of the making of the film, The Prince and the Showgirl, starring our old friend Laurence Olivier and Marilyn Monroe.

Your introduction carries a touching reference to me, suggesting that my imagination and my youthful antics fired your imagination even as a small child, and that I was in no small way responsible for your choice of a show business career. I am delighted it did. Yours has been an excellent life. What else are big brothers for? We are a constant example for good or ill. However, you end by saying you could not have written this book during Marilyn's lifetime. I can't think why not.

What is certain is that you could not have written it during MY lifetime. Good heaven's man, nothing happened between you. Your behaviour in some quarters might be regarded as impeccable to be expected of a Christ Church man but in my view you blotted the escutcheon of the Clarks for generations to come. What a relief it is that our father never lived to read it.

There you are, skinny dipping (I believe the phrase is) with the most sought-after woman in the world and you avert your eyes. She invites you into her bed and you turn your back on her. For reasons best known to herself, the woman chases you shamelessly, and you retain the high moral stance. I can only think somewhere I failed you, and it is distressing. You give all sorts of noble reasons the woman was on her honeymoon; she was vulnerable; you feared for your job. The last excuse I find the most galling. I know you were only 23, fresh down from University but you are a Clark.

Surely you picked up something in three years at Oxford. If Larry Olivier had given you the push you still had the intellect to find another job. But more important, you could have dined out on the story for years. Your market value would have soared and I could have touched you for the odd fiver as you did me when you were a spotty schoolkid at Eton.

But I cannot help but wonder if you are playing the straight bat with me, Young Colin. The narrative of the book is so minutely detailed. If, as you say, you committed nothing to paper for 44 years, let alone to those nauseating diaries you insisted on keeping from an early age ("Went fishing, caught a tiddler. We had jelly for tea and I was sick. Nanny was livid..." and all that sort of thing) how come the quotes are spot on? Was the book written with some feelings of regret and that with the passage of time an otherwise innocent encounter took on greater colour, or had you penned it somewhere and hung on to it just in case you needed something extra to boost a future book? Let's face it afterYounger Brother, Younger Son, your delightful memoir which clearly stars our oft rakish father and me, you needed something with a bit of a bite to make 'em sit up and notice.

But having said all this, it was a delightful vignette touchingly innocent and capturing for so many of us who were always in love with Marilyn, a reminder of her beauty and vulnerability. I also genuinely believe you would have wished to be around to save her on the fateful day when the world lost a goddess. I have rarely met a chap who wouldn't. The only difference is I would have swept her off her feet all those years before. Pointless regretting, but of course, you aren't me.

Nonetheless, I'm still in the next world as I was in the first Your ever loving brother,

Alan