‘How should I know?’ I said. ‘I don’t even believe in ghosts.’

‘Let’s go and see if he’s there,’ she said. ‘If I see him too then it will be like corob … like crob … proof.’

‘Okay,’ I said.

We wandered arm in arm up King Street towards Covent Garden.

There was a great absence of Nicholas the ghost that night. We started at the church portico where I’d seen him and, because Lesley was a thoroughgoing copper even when pissed, did a methodical search around the perimeter.

‘Chips,’ said Lesley after our second circuit. ‘Or a kebab.’

‘Maybe he doesn’t come out when I’m with someone else,’ I said.

‘Maybe he does shift work,’ said Lesley.

‘Fuck it,’ I said. ‘Let’s have a kebab.’

‘You’ll be good at the Case Progression Unit,’ said Lesley. ‘And you’ll be …’

‘If you say “… making a valuable contribution” I will not be held responsible for my actions.’

‘I was going to say “making a difference”,’ she said. ‘You could always go to the states, I bet the FBI would have you.’

‘Why would the FBI have me?’ I asked.

‘They could use you as an Obama decoy,’ she said.

‘For that,’ I said, ‘you can pay for the kebabs.’

In the end we were too knackered to get kebabs, so we headed straight back to the section house where Lesley utterly failed to invite me to her room. I was at that stage of drunk where you lie on your bed in the dark and the room goes whirling around you, and you’re wondering about the nature of the universe and whether you can get to the sink before you throw up.

Tomorrow was my last day off, and unless I could prove that seeing things that weren’t there was a vital skill for the modern police officer, it was hello Case Progression Unit for me.

‘I’m sorry about last night,’ said Lesley.

Neither of us could face the horrors of the kitchenette that morning, so we found shelter in the station canteen. Despite the fact that the catering staff were a mixture of compact Polish women and skinny Somali men, a strange kind of institutional inertia meant that the food was classic English greasy spoon, the coffee was bad and the tea was hot, sweet and came in mugs. Lesley was having a full English breakfast; I was having a tea.