Damon Galgut, the South African writer, has been quietly forging a fine body of work over recent years. He has been shortlisted for the Booker prize and other awards. His books include The Good Doctor and In a Strange Room, both of which contain reflections on loneliness, solitariness and unease. Galgut is the spokesman of the ill-at-ease and the alienated.

So a fictional biography of EM Forster, whose homosexuality gave him endless angst and a perpetual sense of estrangement, makes sense as a project for Galgut. It may be that Galgut’s anxiety, his loner’s sensibility, is what drew him to Forster. He has called his novel Arctic Summer, the title of a Forster novel that was never finished. You have the sense that Galgut’s novel is designed to shape into one book many of the apparently competing aspects of Forster’s ambivalent relation with both fiction and sex.

But it is not all sturm und drang. There are some slyly funny accounts of Forster’s meetings with absurd maharajahs and social-climbing British officials; Galgut has a keen eye for the absurdity of the small princely palaces Forster frequented, most prominently in his employment by the eccentric maharajah of Dewas. The maharajah aids and abets his sexual needs, and even provides a young barber to take care of them.

At one point, back in England when he has been blocked for years, Forster tells Virginia Woolf, that he is no novelist, and she agrees rather too readily. He wonders, as Galgut puts it: “What earthly use are novels? How do they help anyone?” Not long after, in the grips of inertia, Forster suddenly sees that the way forward is to engage with the mystery of India, which had repelled him on his first visit to the Marabar Caves. He is released from torment and finishes A Passage to India to wide acclaim.

Forster had two great loves in his life, one Egyptian and one Indian. The Indian, Syed Ross Masood, was a charismatic student in England when he was taught Latin by Forster; each took to the other and they continued to meet up for many years, both in England and India. They were so close that Forster came to believe that the relationship could be consummated. But when one evening Forster kissed him, Masood rejected him, pushing him away. Forster was both horribly embarrassed and deeply wounded. Later, his friend told him he had married, and Forster was plunged into depression. For all that, their friendship persisted and over 17 years they continued to meet and exchanged highly charged and affectionate letters.

Forster’s second great love was an Egyptian, Mohammed el-Adl, a tram driver in Alexandria. Forster met him when he was sent to Egypt in the role of “searcher”, where his task was to interview the war-wounded in hospital to see if they knew anything of the fates of those who were unaccounted for. Mohammed’s caresses and natural warmth did wonders for Forster. Their relationship lasted many years, despite the risks and the very obvious disparity in their backgrounds and despite the fact that Mohammed, too, went on to marry and father a child. On his voyages to and from India, Forster always tried to meet up with Mohammed in Port Said and when Mohammed was ill and dying, Forster did everything he could to help him.

Galgut has followed the known sources fairly closely: Forster’s smothering mother, Lily, his travels to India, his necessarily suppressed homosexuality, his fear that he would die a virgin and the two loves in his life, his writing – all are skilfully woven into a compelling account of Forster’s writing and of his sexual preoccupations and longings. A vast amount of research lies behind this fine book, but the research is never intrusive. It is exemplary in its tone and its insights – a difficult feat to achieve.

Arctic Summer is published by Atlantic Books (£8.99). Click here to buy it for £7.19