Margrave of the Marshes by John Peel and Sheila Ravenscroft

In the midst of the large part of Margrave of the Marshes which was completed after her husband's death, Sheila Ravenscroft quotes a 1977 diary entry, in which Peel responds to criticism of his refusal to make more fuss on air about the death of Elvis Presley. "I prefer to remember those who have died in their proper context," he wrote, "filling some greater or lesser niche in everyday life, rather then distorting my memory of them in a welter of terminal sentiment."

Many aspects of the glut of multi-media hagiography which has followed Peel's passing have inclined one to think "Amen to that." Not least the determination of the very Radio 1 bosses who'd been itching to get rid of him for years to establish themselves as keepers of his eternal flame. But while there's something undeniably appealing about the idea of Peel reaching out from beyond the grave to wipe away the thick layer of bullshit with which his legacy is becoming encrusted, a post-deathbed conversion to unadorned truth-telling would have ultimately represented a betrayal of everything he held dear.

This was, after all, the man who began his showbiz career pretending to be a friend of the Beatles in order to further his sexual education at the hands - and other parts - of semi-innocent Texan high-school girls, and ended it as Radio 4's cosy custodian of the pleasures of the domestic hearth. And the huge DNA-cluster of contradictions from which Peel's identity was constructed (public school educated man of the people, counter-cultural sage and establishment figure, millionaire ally of struggling musicians, tireless enthusiast and unrepentant curmudgeon) finds an aptly perplexing reflection in this fragmentary and multi-faceted volume.

After a suitably tender introduction from his four children, the first - Peel-penned - section of the book rather suffers from its author's long years of preparatory hard labour at the coalface of his own mythology. Even headline-grabbing revelations about the rape and sexual abuse he suffered at Shrewsbury school come swaddled in that familiar protective layer of gentle wit acquired from his close reading of James Thurber and P G Wodehouse. Then, on page 165, Peel's younger self is left standing on the threshold of a Mexican brothel by his autobiographer's untimely passing. At this juncture, the story of the man who had still yet to acquire the name by which everyone later came to know him is entrusted to the second wife he would not meet for a further six years. There seem to be two ways Margrave of the Marshes can go from here. It can either sweep the detritus of Peel's decadent 1960s - the 15-year-old first wife was only the start of it - firmly under the carpet. Or it can add to that burgeoning biographical sub-genre in which the less famous spouse of a much-loved public figure (cf John Bayley and Iris Murdoch, Sheila Hancock and John Thaw, Pamela Stephenson and Billy Connolly) sells more copies of a book about them than anyone would have thought possible by being more candid about their flaws than decency should have allowed.

It is much to Sheila Ravenscroft's credit that she takes neither of these courses. True, the two-thirds of this book to which she has put her name does contain the odd bit of gentle posthumous score-settling: "Occasions when John's needs didn't square with those of the children were particularly tough for him," apparently. But the overall tone manages to be both tender and acute, and Peel's real feelings emerge much more clearly without the semi-ironic gloss which he was no doubt planning to apply to them. In fact, the despairing tone of another diary entry ("The waist of Peel moves inexorably outward. Eleven stone eleven pounds this morning - where will it end?") combines with an unabashedly lyrical description of life onboard Radio London's pirate ship to sum up perfectly his life's opposing poles of private melancholy and professional exultation.

In the rough notes to his agent which are printed as an appendix, Peel threatens "as many pages as you like of saccharine stuff about babies" and "real danger of book degenerating into a hymn of praise to Sheila", so no one can say the finished volume's well-developed family scrapbook element is not what he would have wanted. But the fascinating thing about Margrave of the Marshes is that, far from representing the final triumph of Peel's Home Truths self over his Radio 1 self, it ultimately underlines the one truth that Peel - self-deprecating egotist that he was - understood better than anyone else, which is that the thing that really mattered was the music.