Toby the dog bites Punch, who beats Mr Scaramouch, Toby’s owner, to death. He then goes home and throws his baby out of the window and beats his wife Judy to death. He falls off his horse and kicks the doctor in the eye. The doctor attacks him with a stick, but he grabs that and beats the doctor to death. He rings a sheep bell outside a rich man’s house, and when the rich man’s servant remonstrates with him Punch beats him to death. At that point, my ice cream melted and slopped all over my shoes.

The Tragical Comedy, or Comical Tragedy, of Punch and Judy as told to John Payne Collier by Giovanni Piccini in 1827. Not very hard to get hold of, once you know what you’re looking for. After the show, Lesley and I showed the Professor our warrant cards and he was happy to hand over the hard copy of the script. We took it over to the Roundhouse on the corner of New Row and Garrick Street, and settled in to read it with two double vodkas..

‘It can’t be a coincidence,’ I said.

‘You think?’ asked Lesley. ‘Something is using real people to act out this stupid puppet show.’

‘Your governor’s not going to like this,’ I said.

‘Well I’m not going to tell him,’ said Lesley. ‘Let your governor tell my governor that the fucking ghost of Mr Punch is knocking people off on his patch.’

‘You think it’s a ghost?’ I asked.

‘How should I know?’ she said. ‘That’s what you magic cops are for.’

The Folly has three libraries: one, I didn’t know about back then, number two was a magical library where the direct treatise on spells, forma and alchemy were kept, all of them written in Latin and so all Greek to me, and number three was the general library on the first floor next to the reading room. The division of labour was clear from the start: Nightingale checked the magic library, and I hit the books in the Queen’s English.

The general library was lined with enough mahogany to reforest the Amazon basin. On one wall the stacks went all the way to the ceiling, and you reached the top shelves by using a ladder that slid along on shining brass rails. A row of beautiful walnut cabinets held the index cards, which were the closest thing the library had to a search engine. I caught a whiff of old cardboard and mildew when I opened the drawers, and it comforted me to think that Molly didn’t go so far as to open them up regularly and clean inside. The cards were arranged by subject, with a master index arranged by title. I started by looking for references to Punch and Judy, but found none. Nightingale had given me another term to search for: revenant. A couple of false passes with the index cards led me to Dr John Polidari’s Meditations on the Matter of Life and Death which, according to the frontispiece, had been published in 1819. The same page had a notation in Latin written in an elegant looping hand: Vincit qui se vincit, August 1821. I wondered what it meant.