OUR THREE SELVES; The Life of Radclyffe Hall. By Michael Baker Morrow. 386 pp. 17.95.

RADCLYFFE HALL, 1880-1943, is Britain's most famous lesbian. She was highly visible at a time when most inverts stayed in the closet, and in 1928 she published a novel, The Well of Loneliness, the subject of which was the experience of female homosexuality. "So far as I know," she wrote, "nothing of the kind has ever before been attempted in fiction."

Although The Well is a courageous and sincere book, it is not a very good one. When her publishers were prosecuted for putting out an "obscene" work, English writers were solidly behind her on the principle of free expression, but inhibited from giving effective support by their reservations about the novel's literary value, and it was banned. She was luckier in the United States. Covici Friede, her publishers, exploited the inevitable prosecution to boost sales, and with vociferous support from American writers, the ban was reversed on appeal.

John -- as Marguerite Radclyffe Hall was known to everyone -- was not averse to a spot of martyrdom. She believed homosexuality was a congenital affliction, and that love must involve suffering and sacrifice. When a caricature was published showing her nailed to the cross (in her Spanish sombrero, with a nude girl dancing athwart her thighs) she was, as her biographer stresses, appalled by the blasphemy. The reader may suspect that she was also stirred; soon she was suffering from mysterious raw wounds in the palms of her hands, like stigmata. Her personal fantasy seems to have been to fill a gap somewhere between Jesus Christ and Oscar Wilde.

John, the unwanted child of an unhappy marriage, appears to have become her own father figure, adopting in adulthood a gruff masculine manner and boasting of her inability to boil an egg. Her life companion Una Troubridge, formerly an admiral's wife, was her housekeeper and secretary, and corrected her bad spelling. The Unlit Lamp, the first and best of her eight published novels, was not written until she was 40.

Her first long involvement was with an elderly married woman, Mabel Batten, known as "Ladye." After a quarrel between John and Ladye over John's new attachment to Una, Ladye had a stroke and died. The remorseful John, with Una in tow, became committed to years of s,eances in which Ladye, from beyond the grave, directed the new couple's life. Ladye, John and Una are "our three selves."

OBSESSIONAL DEVOTION is the keynote. John and Una were devoted to Ladye, each other, John's writing, their Catholic faith and their dogs. A paradoxically conventional pair, they expressed conventionally unenlightened views about Jews and the servant class, and were keen on the Italian Fascists. It'simportant to keep remembering that people with such values nevertheless bleed and suffer and get their hearts broken.

Bleed and suffer they did, continuously. Both were subject to endless ailments, which Una especially used as emotional currency in her conflicts with John. Michael Baker spares us much of the available information about hemorrhoids and digestive disturbances, and handles gynecological detail warily. John would have approved of a male biographer, since she had no time for other women except socially; she dismissed that formidable publisher Blanche Knopf, announcing, "I am accustomed to dealing with men in business . . . I find it both difficult and tedious to deal with a woman."

She has managed to keep even Baker at arm's length, in spite of his thorough research which adds considerable detail to the information already available (in Lovat Dickson's dutiful Radclyffe Hall at the Well of Loneliness, Una Troubridge's hagiographical The Life and Death of Radclyffe Hall, Richard Ormrod's feeble Una Troubridge: The Friend of Radclyffe Hall). He has not, however, applied the artistic need-to-know principle consistently -- unless you feel you need to know, for example, the affectionate pet- names that various persons in this saga gave to their hot-water bottles.

Baker is resolutely agnostic -- about the spiritualism, the religiosity, the grand and petty passions, the hot-water bottles. He sometimes felt, reading Radclyffe Hall's books, that she could have been a deeper, more angular, altogether more original writer than she allowed herself to be. Whatever it was that held her back may have got in his way, too.