His morning today had begun in Iffley. He had caught a few hours’ sleep inside the porch of St Mary the Virgin. He had risen at 4 a.m. before the lights in the vicarage switched on, brushed his teeth, picked out what to wear. He kept in his backpack, wrapping the one or two sacred texts on the subjects he was winnowing: a pair of Primark swimming trunks with a net layer that was easy to wash, three pairs of socks, a shirt, a pullover, plus a toothbrush/toothpaste, a comb, a water bottle, a torch, a penknife, and a bar of L’Occitane verbena-scented soap.

After completing his exercises on the grass, he had jogged, backpack on, along the towpath to the train station, which opened at 4.30 a.m., and sat on a bench. No one threw him out ever, or talked to him; he had no conversations with anyone – ‘I try not to draw attention to myself.’ Dyer wouldn’t have noticed him, necessarily. In his parallel dimension, he fitted like a trout into his surroundings.

At 6 a.m. he walked from the station to McDonald’s in Cornmarket. There he ate an egg and cheese McMuffin.

At 9 a.m., he entered one of the university libraries, producing his Bodleian Reader card. He had yet to climb the art-deco staircase to the Taylorian. His three favourites: the Vere Harmsworth Library in Parks Road, the Sackler Library in St John’s Street, and the Social Science Library in Manor Road.

Invariably, he spent his day in one of these reading rooms, studying or napping. Twice a week for several months he would wash his clothes in the men’s toilet of the Social Science Library, hanging his socks and pants out of the window to dry, or on sunny days spreading them on the hedge beneath, while taking his lunch on the grass strip beside St Catherine’s. But George, the doorman, had recently grown suspicious. He had approached Rougetel while he was reading a biography of Max Weber, and warned: ‘We’ve been watching you for some time.’ Rougetel had since found an alternative wash basin, in a steam-room on the top floor of the Westgate shopping centre; the door was locked, but he could prise it open with his penknife.

The pattern of his life emerged like a brass rubbing with each loping step.

In the afternoons, he slept for an hour or two in a leather armchair in the Oxford Union – his radical grandmother had given him a lifetime’s membership. His eyes became glinty when Dyer asked what he did to stay afloat, as if the subject bored him. ‘Money? That’s just numbers.’