University College Hospital takes up two whole blocks between Tottenham Court Road and Gower Street. Founded in the nineteenth century, its main claim to fame was as the teaching hospital for the University College of London and the birthplace of one Peter Grant, apprentice wizard. Since that momentous day in the mid-1980s, half the site had been redeveloped into a gleaming blue and white tower that looked as if a bit of Brasilia had crash-landed in the middle of Victorian London.

The lobby was a wide, clean space with lots of glass and white paint marred only by the large numbers of sick people shuffling around. Police officers spend a lot of time in A&E, since you’re either asking people where they got their knife wounds, dealing with the violently drunk or being stitched up yourself. It’s one of the reasons so many coppers marry nurses – that, and the fact that nurses understand about unreasonable shift systems.

Beverley’s acolyte was a nurse, a pale skinny one with purple hair and an Australian accent. She stared at me suspiciously.

‘Who’s this?’ she asked Beverley.

‘This is a friend,’ Beverley said and put her hand on the woman’s arm. ‘We tell him everything.’

The woman relaxed and gave me a smile full of hope. She looked like one of the Pentecostal teenagers from my mum’s second-from-last church. ‘Isn’t it wonderful to be part of something real?’ she said.

I agreed that being part of something real was indeed wonderful, but it would be groovy if she could tell me what she’d seen. I actually used the word ‘groovy’ and she didn’t even flinch, which was worrying on so many levels.

According to her, a cycle courier had been brought in by ambulance following a road traffic accident, and while he was being treated he’d kicked the attending doctor in the eye. The doctor had been stunned rather than seriously injured and the cycle courier had run out of A&E before Security could nab him.

‘Why bring it to us?’ I asked.

‘It was the laughing,’ said the nurse. ‘I was going back to the treatment bay when I heard this screeching laugh, like a mynah bird. Then I heard Eric – Dr Framline, that’s the doctor who was injured – I heard him swearing, and then the cycle courier comes charging out of the bay and there’s something wrong with his face.’

‘Wrong, how?’ I asked.

‘Just wrong,’ she said, displaying precisely the characteristic that makes eyewitnesses such a useful part of any police investigation. ‘He went past so fast I didn’t see much but it just looked … wrong.’