‘That at least will not pose a difficulty,’ said Nightingale. ‘Although it does mean we’ll have to postpone the capture operation until late tonight.’

‘You’re going ahead with this?’ asked Lesley. She looked at me with concern. I gave my best shot at insouciance, but I suspect it came out looking more like unfounded optimism.

‘I believe, Constable, that this is our only option,’ said Nightingale. ‘I’d be most grateful if you could brief Inspector Seawoll and ask him to stand ready in Covent Garden at eleven.’

‘As late as that?’ I asked. ‘Henry Pyke might not wait that long.’

‘We won’t get our warrant until eleven at the earliest,’ said Nightingale.

‘And if this doesn’t work?’

‘Then it’ll be Lesley’s turn to come up with a plan,’ said Nightingale.

We drove back to the Folly, where Nightingale vanished into the magic library, presumably to bone up on his revenant-tracking spells, while I went upstairs to my room and took my uniform out of the cupboard. I had to hunt around for my helmet, and eventually found it under the bed with my silver whistle, absurdly still part of the modern uniform, inside. Since my latest phone hadn’t survived Tyburn’s fountain I retrieved the police-issue Airwave from my desk and slotted in its batteries. As I packed it in my carryall with my uniform jacket I realised that the room still looked like somebody’s spare bedroom, somewhere I was just staying in until something better came along.

I slung the carryall over my shoulder and turned to find Molly watching me from the doorway. She cocked her head to one side.

‘I don’t know,’ I said. ‘But we’ll be eating out.’

She frowned.

‘I’m the one who’s going to be out front,’ I said, but it didn’t seem to impress her. ‘He’ll be fine.’

She gave me a last sceptical look before gliding away. By the time I was out of my room she was nowhere to be seen. I went downstairs and waited for Nightingale in the reading room. He emerged half an hour later dressed in his ‘working’ suit and carrying his cane. He asked me whether I was ready, and I said that I was.

It was a beautiful warm spring evening, so rather than take the Jag we strolled down past the British Museum before cutting through Museum Street and into Drury Lane. Even though we’d taken our time we still had hours to spare, so we popped into a curry house near the Theatre Royal, with the promising name of the House of Bengal, for dinner.

As I checked a menu mercifully free of potatoes, thick crust pastry, suet and gravy, I realised why Nightingale liked to eat out so much.