It took him a few minutes to collect his violin, his prayer-kit and a change of clothing from Spielman’s house. Returning to the prayer-house, he saw a workman on the other side of the street in blue overalls and flat cap, about the same height and build as the plumber at the bus-stop. He ducked into the waiting car, covering his face with a talit-bag and telling Spielman, at the wheel, to get a move on. Was he being followed? It hardly mattered now, but he longed to get away and breathe a different oxygen.

They slipped through London’s suburban sprawl, past Edmonton where Dr Steiner lay in his lonely grave. Avoiding the A1 highway for fear of police checkpoints, they sidled up through flatland East Anglia to the industrial north-east, stopping three times for petrol, prayers and a chance to admire the yellowing beauty of an early-summer countryside. Two dark men in long black coats swaying over a crop-filled meadow might have aroused local suspicions, but the pair felt safeguarded by the merit of their journey and in the car, for much of the way, they sang a medley of Medzhiner tunes.

It was dark when their Vauxhall pulled up outside Oldbridge Yeshiva, a thriving college concealed behind the residential frontages of three terraced houses. It consisted of a prayer-hall, tutorial rooms, kitchen and dormitory quarters. Dovidl was assigned a bed in a box-room, shared with three others. It was so narrow that only one man could rise and dress at a time, but the cellmates were courteous to the newcomer and he experienced no friction.

His formal instruction commenced the next morning, after prayers and a generous breakfast, with a Talmud session that left him floundering. It began with two men clutching a prayer shawl, or talit, each claiming ownership, so far as he could tell. But the text veered off the disputed point into unconnected byways: the validity of an oath, the meaning of money, the nature of sacrifice, the prophet Elijah – all without pause or punctuation, and with contrasting opinions coming left and right from rabbis in different centuries and countries. At the end of two hours he felt dejected, defeated, ready to leave.

After coffee, the students paired off in the prayer-hall to revise the half-page they had just been taught. Dovidl was put together with Yoel, formerly of Vilna, to whom he expressed bemusement. ‘But that’s what makes Talmud so engaging,’ said Yoel. ‘There are usually three separate issues being discussed, linked by one, or more, of the thirteen recognised methods of exegesis. Each issue has at least two sides, and to each side there are conflicting opinions. On each opinion, there are fifteen centuries’ worth of commentaries, right up to the present day. The trick is to keep the main issue in mind while whittling down subsidiary arguments, one by one. When you get it right, there is nothing more satisfying.’