"Did cruising start in the fifties?" muses Derek Jarman in his always entertaining if often painful journals Smiling in Slow Motion (Century 16.99), writes Christopher Gray.

The reference is, of course, not to holidays at sea but to the determined, careless trawling for sex with strangers practised by many gays, including Mr Jarman, who with cantankerous resistance to convenient labels - that way lies another closet - always preferred to be called 'queer'.

He could have found the answer to his question in Lost Years: A Memoir 1945-1951 (Chatto & Windus 25) in which novelist Christopher Isherwood chronicles all too thoroughly the energetic cruising (the word is used) of handsome young males that occupied his off-duty hours, usually on beaches, when he was working as a Hollywood scriptwriter in the immediate post-war years.

Quoting approvingly from the great poet with whom in the late thirties he fled across the Atlantic to escape the looming war, he tells us: "Auden says that it's important, in considering a sex relationship, to say exactly what the partners did in bed." Others might think it gratuitous - a view which perusal of this book, at times a real glimpse into a cesspit, might confirm.

Still, there are rich rewards to be found in its 350-odd pages describing his heady, carefree days in tinseltown. It is a period for which the famous 'camera' of his mind is swapped for the impressionistic sweeps of a painter, since he kept no detailed journal and has pieced together what he can from the bald jottings in his engagement diary.

The job was begun in 1971 but was put aside without being prepared for publication when Isherwood became involved in writing Christopher and his Kind, the autobiographical work which made his name as a champion of gay lib.

Here again, he employs the device of third person narrative, on the basis that the 'Christopher' of those days is very different from the 'I' engaged in the writing of the memoirs. While he is always in the foreground, Chaplin, Garbo, Cole Porter, Truman Capote, Benjamin Britten, Gore Vidal, Graham Sutherland, Stravinsky (a captivating portrait) and other big names abound. I found it endearing rather than irritating (as some critics have complained) that details of his conversation and actions with these people are often lost in the mists of time, or alcohol. No such problem with Derek Jarman, whose meticulously-kept journals cover the period from May 1991 (when the story of his life told in Modern Nature ended) to within a fortnight of his death from Aids in February 1994. Awesomely brave when confronted with the ravages of the disease - the night sweats, the erupting skin, the steady decay of "that one talent which is death to hide" - he maintains a jovial banter with his readers at even the ghastliest times. We find him working hard on both his writing and film directing (including completion of a biopic on Wittgenstein scripted by Oxford English professor Terry Eagleton); coping with all the interviews and the like that resulted from his status as a high-profile Aids patient and campaigning homosexual; tending his beloved garden at Prospect Cottage, by the sea at Dungeness; enjoying the tender loving care of his long-term partner Matthew Collins; making regular trips to London and to his old cruising scene of Hampstead Heath where now his main object seems to be the conversational comfort of strangers.

A better writer, I think, than film maker, he constantly surprises with an exquisite turn of phrase, as in his unforgettable and instantly recognisable portrait of a supermarket checkout assistant: "The tired lady forces the food past the electronic eye like stuffing a foie gras goose, beep, beep, beep."

And all the while, he was hearing about and mourning the death of old friends, many also sufferers from Aids, and preparing for his own final cruise, building - as D.H. Lawrence put it in one of his last poems - the ship of death for his journey into oblivion.