Among those often available to make up a four was Ivan Idelson, a chess Blue, who was doing a PhD in some abstruse department of mathematics. Brown-eyed and black-haired and, I assumed, of Russian origin (he called himself Ivahn, although later in life he anglicised the pronunciation as Eye-v’n), he rented a room at 5 Jordan’s Yard, a mews of decrepit terraced houses across from the side gate of St John’s. I would find him wearing a claret-coloured smoking jacket and, quite often, playing Chopin on the black overstrung piano in the front room. He lived with a buxom, horsey, boss-eyed girl called Sonya. I accompanied her, because she asked me, to a point-to-point at Cottenham, a village near enough to Cambridge to be reached by bicycle. We watched the races and were spattered with mud from the loud hoofs and then we pedalled home. I went up the sagging stairs with her to the room she shared with Ivan and she told me, hugging her knees as she rocked on the bed where I was sitting, that she had taught him everything he knew about sex.
