What caused offence was the subject matter of female homosexuality, or ‘inversion’ as it was called at the time, and the possibly worse hint at female orgasm, at a time when women – even those respectably married – were meant to barely experience physical desire unless they were ‘bad women’, prostitutes or akin to vampires.

The author, Radclyffe Hall, was born on 12 August 1880 and christened Marguerite. Her parents separated while she was still a baby and the subsequent relationship with her mother and stepfather was minimal. Marguerite was a second child, the first having died in infancy. Her mother disliked her from birth, frequently remarking how much the child resembled the husband she had grown to detest. A nurse, a governess and her grandmother seem to have had most hand in her upbringing. Her stepfather was an Italian who taught singing at the Royal College of Music. Marguerite was musical herself, and began composing songs and poems allegedly from the age of three.

Her mother was given to violent rages, often beating the child and, on one occasion, striking the grandmother. Not surprisingly, Marguerite left home as soon as she was twenty-one and became financially independent, inheriting the remains of a trust fund from her father, and taking the grandmother to live with her in Kensington. Now began what her first biographer and longtime partner Una Troubridge described as a life of ‘pleasant pastime’ and remorseless idleness, mainly spent hunting, travelling, ‘anything but mental effort which was represented … by occasional verses’. Three volumes of her verse were published before 1908, many of them set to music by contemporary composers, with one song, ‘The Blind Ploughman’, being later performed by Dame Clara Butt, Feodor Chaliapin and Paul Robeson to raise money for those who had lost their sight in the Great War.

In her teens Marguerite began to be attracted to other girls and women. She already thought of herself as different. Her mother had disliked what she saw as her masculine appearance and Peter, as Marguerite had now started to call herself, began to emphasize it by her choice of tailored clothes. Though not strictly autobiographical, the account of Stephen’s childhood and adolescence that forms the first book of The Well of Loneliness is in many respects a psychological parallel to Radclyffe Hall’s own development.

Physically, too, Stephen resembles her creator, with her aquiline features, slim hips and broad shoulders. She loves horses and dogs, and insists on riding astride instead of side-saddle as ladies were supposed to. Stephen’s parents had hoped for, and indeed expected, a boy, but Stephen’s boyishness, although understood by her father, who reads the work on ‘inversion’ by the contemporary German sexologist Magnus Hirschfeld, under the soubriquet Karl Heinrich Ulrichs, is deeply resented by her mother, just as Radclyffe Hall’s mother resented the boyishness of the real-life daughter.

At the end of the first book of the Well there is an episode which has no documented counterpart in Una Troubridge’s biography, The Life and Death of Radclyffe Hall. Stephen becomes friends with a young man, Martin Hallam, who is prepared to treat her as an equal. He is presented in contrast to the plumply odious Roger, the son of her parents’ friends, with whom she is taken to play along with his sister Violet who, rather like the Violet Elizabeth of the Just William books, is an exaggeratedly girlie girl. Roger is a bully, taunting Stephen for riding astride and criticizing her mother for allowing it. In response, with a temper as fiery as Radclyffe Hall’s own according to the Life, Stephen wants to fight him. She learns to fence and goes in for body building in order to be as strong as a young man. Meanwhile Martin Hallam’s friendship turns to physical love and he proposes. Stephen is horrified, ‘repelled’, and sends him away. In contrast, her first physical affair, after a series of what used to be known as ‘schoolgirl crushes’, brings home to her both her real sexual nature and its attendant problems. She rescues a small dog belonging to a married American actress and invites its owner, Angela, to her home. During her visit Stephen falls ‘quite simply and naturally in love, in accordance with the dictates of her nature’.

Radclyffe Hall’s purpose is as an apologist in the best sense, for she sees female homosexuality as born not made, following the ideas of the sexologist Havelock Ellis – even though it could be argued that Stephen’s parents’ expectations of a son, and her mother’s rejection of her daughter, provide a Freudian blueprint for the role of nurture as well as nature in determining sexuality. Hall is particularly anxious to emphasize Stephen’s position as ‘midway between the sexes’, and therefore not the result of a wilful choice, in order to justify her own very active homosexuality, which she embraced in spite of her espousal of Roman Catholicism.

Also in keeping with Havelock Ellis’s views, Stephen believes that ‘inverts were being born in increasing numbers’. This forms part of Hall’s justification for going where only ultimate condemnation or misinterpretation had gone before, apart from the more subtle hints in Virginia Woolf’s Mrs Dalloway and To the Lighthouse. Both novels were in a sense precursors to Woolf’s full-blown, witty exposition in Orlando of her protagonist’s ‘vacillation from one sex to the other … the mixture in her of man and woman’. Interestingly Orlando shares with Stephen a tender-heartedness towards animals and ‘could not endure to see a donkey beaten or a kitten drowned’. Hall herself sees this as part of ‘the terrible nerves of the invert’, a sensitivity that makes Stephen know intuitively what people are thinking and feeling.

It was Hall’s first long-term lover, Mabel Batten – always known as Ladye – who had named her ‘John’, the name by which she was to be known to Ladye’s successor, her cousin Una, and subsequently to generations of readers of The Well of Loneliness.