The remaining huddled rags now somehow shifted from disorderly lumps to crisp cardboard tickets. On each a name was written in neat ink and beneath it a signature and a number. I stretched forward to read one closely.

RECEIVED: Thomas Knapp (aged 4)

FOR THE SUM OF: £11 2s. 5d.

RECUPERATION COST: £31

SIGNATURE: Frederick Knapp (father)

‘Thomas Knapp!’ I said. ‘I know that name.’

‘Do you, boy? It is not impossible.’

‘Thomas Knapp is what underbutler Briggs’s shoehorn says! I’ve heard it calling.’

‘Have you indeed?’

‘I am certain of it, but why, Grandfather, why would it say that?’

‘Patience, child, we are proceeding there.’

‘Thomas Knapp, that’s what it says.’

‘Pawned people were taken from the slums, so that they might be put to great use. The first were taken up to Bay Leaf House and, after a time there, some skilled Iremongers working with these pawned ones (known often enough simply as “tickets”), feeding them scraps, discovered that there was a simple way of keeping people benumbed, useful and hard-working, but unthoughtful. A certain amount of London dirt ground up into a powder or paste can stop a person thinking too much, can unencumber him of memory. A mixture of castor oil, engine oil, ground London dirt, Thames water, oakum, saltpetre. This powder can be easily put in poor food, in bread, or simply, if sweetened slightly, just portioned out upon a spoon. This has been very advantageous for us. And yet.’

‘And yet, Grandfather?’

‘And yet. There have been complications, there is a great problem.’

The tickets flew away now. The slate picked itself up and returned itself to Grandfather’s coat. The old man looked very troubled.