Only, I recognised the face. I’d first seen it on a cold January morning and it had introduced itself as Nicholas Wallpenny – late of the Parish of Covent Garden. But no, not Nicholas Wallpenny, it was Henry Pyke. It was always Henry Pyke, right from the start, from the portico of the Actor’s Church, making the most of his chirpy cockney impression. Well, at least it explained why Wallpenny wouldn’t show himself in front of Nightingale. It also meant that the scene at the church that had led me to my impromptu excavation of a priceless London landmark had been just that – a scene, a performance.

‘Help, help,’ cried one of Macklin’s companions, ‘murder!’

Some things are universal: birds got to fly, fish got to swim, fools and policemen got to rush in. I managed to restrain myself from shouting ‘oi’ as I ran forward, and as a result got within two metres before Henry Pyke saw me coming. I got a very satisfying ‘oh fuck’ expression from him and then his face changed – he became the ludicrous quarter-moon caricature that I had come to know as Mr Punch, spirit of riot and rebellion.

‘You know,’ he squeaked, ‘you’re not nearly as stupid as you look.’

Standard operating procedure for dealing with mad fuckers; keep them talking, sidle closer, grab them when they ain’t looking.

‘So was that you pretending to be Nicholas Wall-penny?’

‘No,’ said Mr Punch. ‘I let Henry Pyke do all the deception, lives to act, poor thing, it’s all he ever wanted out of life.’

‘Except he’s dead,’ I said.

‘I know,’ said Mr Punch. ‘Isn’t the universe wonderful?’

‘Where’s Henry now?’

‘He’s in your girlfriend’s head having carnal knowledge of her brain,’ said Mr Punch, and then threw back his head and shrieked with laughter. I lunged but the slippery bastard turned on his heel and legged it down one of the narrow alleys that connected to Drury Lane.

I took off after him, and I’m not saying that I could feel the spirit of every London thief taker flowing through me as I ran, but consider – we did start outside Bow Street Magistrates Court, and I could no more have not chased him than I could have stopped breathing.