‘Sometimes when I turn up on a Sunday morning, he is still sitting at breakfast saying grace with his youngest kids – he has eleven, amazing. Seeing him like that, I suppose he prefers a quiet life to the risk of playing a live concert where anything can go wrong. Maybe he had a breakdown, or lost his nerve. But then he’ll pick up the fiddle and play the Beethoven concerto, with Joachim’s cadenzas, me picking out accompaniments on the wonky upright. And I think, Wow, what a loss.

‘The only thing he ever asks is that I mustn’t tell anyone, specially not my mam. I must have mentioned that she hates folk like him, and neither of us wants her turning up on his front doorstep accusing him of stealing my blood for Passover. He tells me, quite sharply, not to make fun of her fears, that she does her best for me and I must respect her. I hope he won’t mind my telling you all this, since you’re Jewish also, just like him.’

Is it so obvious? Or has his pathetic mother warned him of my malevolent race? I am tempted to choke the boy and drain his blood just to fulfil her loathsome prejudices, but there are higher priorities to hand.

‘And what if Mr Katzenberg does mind you telling me?’ I needle.

‘Can’t be helped,’ says Peter.

‘You have fallen out with him?’

‘Other way round,’ he says.

‘What happened?’

‘He told me to go away.’

‘When was this?’

‘A month ago,’ says the boy, looking queasy. I retract my chair in case he vomits and squeeze out one last gobbet of intelligence.

‘He caught me outside the Jewish grocery shop on Canning Street talking to his daughter, Basya-Beyla, she’s about my age, dark hair, keen on maths. “Not fitting,” he says. “Our girls do not mix with boys, even our own. If my child is seen talking to a stranger, no one will want to marry her. Please go now, forgive me.”

‘I swear to you, Mr Simmonds, there was nothing between us, me and her. We were just chatting about schoolwork, for heaven’s sake. But the old man puts me in quarantine, as if I’m a dog with rabies. “Please leave now,” he says. “It is best.” He’s not angry. Just detached, and dead set. He cancels his papers from Mr Amin. Then I find out he’s switched to another newsagent. He just wanted to get rid of me, that’s all.’

‘I’m sure he’ll be glad to see you back some day,’ I tell the boy misleadingly, leading him from the tea-table to the purring Jaguar outside. ‘Come, Peter, it’s time to run you home. Your mother will be getting worried.’

‘You won’t tell her, will you?’ he checks.