Shakespeare Tower is one of three residential towers that are part of the Barbican complex in the City of London. Designed in the 1960s by adherents to the same Guernsey Gun Emplacement school of architecture as those that built my school, it was another Brutalist tower of jagged concrete that had acquired a Grade II listing because it was that or admit how fucking ugly it was. However, whatever I thought of it aesthetically, Shakespeare Tower had something that was practically unique in London, something that I was very grateful for as I cautiously skidded the Asbo through snow-covered streets – its own underground car park.

We drove in, waved our warrant cards at the guy in the glass booth and parked in the bay allocated to us. He gave us directions but we still managed to wander around in circles for five minutes until Lesley noticed a discreet sign lost amongst the pipes and concrete abutments. We were then buzzed in by the concierge and guided up to the reception area.

‘We’re here to interview Albert Woodville-Gentle,’ I said.

‘And we’d much rather you didn’t tell him we were on our way,’ said Lesley as we stepped into the lift.

‘It’s just an interview,’ I said to her as the door closed.

‘We’re the police, Peter,’ said Lesley. ‘It’s always good to arrive as a nasty surprise, makes it harder to keep secrets.’

‘Makes sense,’ I said.

Lesley sighed.

The lobby of each floor was an identical truncated triangle shape with undressed concrete walls, grey carpeting and emergency fire exits the size and shape of U-boat pressure doors. Albert Woodville-Gentle lived two-thirds up the tower on the 30th floor. It was very clean. This much institutional concrete makes me nervous when it’s clean.

I rang the doorbell.

Practically the whole point of being police is that you don’t gather information covertly. You’re supposed to turn up on people’s doorsteps, terrify them with the sheer majesty of your authority, and keep asking questions until they tell you what you want to know. Unfortunately, we at the Folly were under instructions to keep the existence of the supernatural if not exactly secret then certainly low-key – all part of the agreement apparently. This meant starting any interview with the question; Oi did you learn magic at university? was right out, and so we had developed a cunning plan instead. Or rather Lesley came up with a cunning plan instead.

The door opened immediately, which told us that the concierge had phoned up to warn the inhabitants. A middle-aged woman with a worn face, blue eyes and hair the colour of dirty straw stood in the doorway. She caught sight of Lesley’s masked face and took an involuntary step backwards – works every time.