He beams again, delighted that the Yiddish-raised infant has intuited his way into an English conversation. No, he chides, he will not be playing tonight, for this is a night of reunion.

At ten, I stretch and prepare to leave. ‘What time shall I come tomorrow?’ I ask.

‘I will collect you from your hotel at eleven,’ says Dovidl, a half-beat too hastily.

‘I have a car and driver, I can come here,’ I offer.

‘No, better that we should discuss things somewhere private and undisturbed,’ he insists. ‘This house, you can see, is like Piccadilly Circus.’

‘Or Covent Garden market,’ I mutter, loud enough for him to hear.

He shoots me a withering look. That pleases me. The past, then, is a faraway country for Mr Katzenberg, but not a neutral state. It has the capacity to strike, through me, at his mask of serenity and monochromatic garb. Missiles and misdeeds from our common locker can still hurt him. He shows me to the front door with almost indecent bustles. I ask him to say goodbye for me to his wife, and walk out without a backward glance.

Alfred grumbles all the way back to the Royal – how could I have kept him waiting so long without so much as a cup of tea, and in a part of town where no one speaks the lingo? I tell him to take the morning off, ignoring his moans now that my quest is accomplished and my riddles are about to be resolved.

The sensation that fills me is not so much elation or relief as raw empowerment. I am no more than moderately pleased to find Dovidl alive, having long given him up for lost. What thrills me beyond the symmetry of reunion is the breathless edge of discovery and the weapon I wield over him. Albert Einstein must have felt like this the night before relativity was revealed. I am about to grasp the mighty truth and, with it, the capacity to destroy a world.

His destiny is finally in my hands. Should I wish, I can avenge myself by exposing his nefarious past to the pure souls he has raised. He will not want them to know of his market tarts and gambling dens, less still of his broken obligations to the family that gave him a home and treated him like a son. My presence has, after the initial welcome, made him uncomfortable. He will not sleep soundly tonight. That is a first payment. But there is more to my elation than the tick of debt collection. For the first time in our relationship, I find myself in control. For the first time in forty years, I have ceased to be a victim of circumstance and can begin to dictate the course of events. Starting tomorrow.