Marco was gaunt and prematurely bald. He spoke with a lisp and a faint French accent. The accent was an affectation: he had a foreign mother but she was Austrian, not French, and his education and upbringing had been in England. His rich parents paid him an allowance and the rent of his flat in Chelsea. He was a dilettante, working on and off in the art world, charming old masters out of old ladies – rewards, perhaps, for the sexual ecstasy that they thought they would never know again. Through his mother, a Frycht, he had an entrée into the grandest families in Europe. Christie’s and Sotheby’s vied for his services as a consultant.

Jomier’s recollection is that his friendship with Marco ended with Marco’s death but, rereading his diaries, he sees that some years before he became ill Marco had imperceptibly passed out of his life. He had returned from New York with a passion for tennis acquired when staying with rich Americans on Long Island. Jomier preferred not to play tennis: he only did so when needed by Tilly for a game of doubles. Now Tilly had a partner in Marco to play with her friends at the Campden Hill Tennis Club or on the courts in Ladbroke Square Gardens.

There was an entry which described Marco coming to Sunday lunch. Tilly had asked one of her single girlfriends. Marco showed no interest. His expression throughout suggested that he wished he was elsewhere. Marco was Henry’s godfather; he had held him at the font. But now Henry was eighteen months old – a tiny Caligula who threw tantrums if he did not get his way. Shrieks. The smell of cabbage and damp nappies. A needy spinster. After lunch, Marco declined to join them on a walk in Holland Park. He took his leave.

Soon after Marco went back to live in New York. It was there that he went down with some rare and fatal illness. He had been flown to a clinic in Austria close to the schloss of his grandparents, Graf and Gräfin von Frycht. It was there that he died. Seeing the back of his friend scuttling away up Holland Park Avenue turned out to have been Jomier’s last view of Marco. There was a memorial service at the Church of the Holy Redeemer in Chelsea and a reception afterwards at his parents’ house in Chester Square. No one seemed to know exactly what had killed Marco: there seemed some embarrassment, even shame. These were the early days of Aids. Jomier wondered whether Marco had found his homosexual experience less vile than he had said; or whether he felt that his quest for experience had led him to try it again with other men – perhaps plunging into the Mineshaft to have anonymous gay sex.