He will make his return, I inform him, in three months’ time at the Royal Albert Hall – on 3 May, forty years to the day since his disappearance. The hall happens to be vacant that night; I made the call and reserved it this morning. He can play whatever he likes, solo recital or concerto with orchestra. ‘They will queue to hear you play “Baa, Baa, Black Sheep”,’ I hyperbolise. I will pay him ten thousand pounds per concert. He will also sign a two-year contract for up to forty performances in Europe, the United States and Japan. I will keep fifteen per cent of his overseas fees, record royalties and broadcast payments, the standard industry terms. By 1993, I predict, when he passes his first million, I will write off the rest of his debt – to me, to my family and to his own destiny. ‘Who knows?’ I say. ‘By then you might be enjoying it so much that you will want to carry on. I had better make the contract renewable.’

His response delights me. This most self-assured of men is fidgeting like a boy who has forgotten his homework. His fingers flutter around the roll of unkosher gums I left lying on the table. He is not so much distressed as disabled, his laser-beam intellect stalled by an insurmountable force. He wriggles this way and that, searching for an emergency exit. I lean back against the locked door.

‘You don’t seriously expect me to play before an audience,’ he implores.

‘Not one audience. Many. Internationally.’

‘But can’t you see that’s completely impossible . . . for a person in my way of life?’

‘I foresee no problem. You will not have to travel or work on the Sabbath, festivals and fast days. Kosher food will be provided at all venues. No scantily dressed girls will appear on stage. All religious requests will be treated sympathetically. I will disclose no more than the bare fact of your forty-year retreat to an unnamed contemplative community. You have no need to say anything more, and I will ensure that your family is kept out of it. No one will have any reason to connect Rabbi David Katzenberg to Eli Rapoport.’

‘What will I tell my wife, my children, my colleagues?’

‘Try the truth for a change. They won’t love you any the less for bringing home a million dollars.’

‘And if I refuse?’

‘I don’t think you have that luxury. You have legal obligations to my firm, quite apart from a moral debt to my family. Should you be foolish enough to try to evade them a second time, I will take steps to ensure that your wife and children are introduced to your interesting past: the clubs, the whores, the betrayal, the theft of a violin. A mysteriously well-researched article will appear in the Jewish Chronicle on the fortieth anniversary of your disappearance. A Daily Mail reporter will turn up on your doorstep. Must I elaborate? It would be a terrible chilul Hashem, a desecration of God’s name. The yeshiva will never live it down.