As we sat on the rug and William revved his cars up and down, I thought about what Mel had told me this afternoon.

Just a stupid drunken snog, that’s all.

But was it, though? Was that all? For however many months, years, Ben had courted my wife behind my back – and I had never realised. It felt like discovering your house had a room you’d never even realised was there. A room full of secrets.

My wife is an attractive woman, men have always been interested in her. Ben took advantage of her in a weak moment. It was a one-off. Now she’s admitted to it, we put it behind us. That’s all there is to it.

The phone rang somewhere in the kitchen.

‘I’ll get it,’ Mel shouted.

She came in a minute later.

‘That was the policeman. He wants us to go in.’

18

The reception area at Kilburn Police Station was tired but functional, lots of grey plastic and bolted-down chairs. It smelled strongly of disinfectant and floor polish, but neither could banish the faint smells of sweat and vomit that greeted us as the doors slid open. An old man with bottle-bottom glasses and a cloud of white hair surrounding his head sat alone on the front row of seats, a small shivering dog in his lap. As soon as William and I sat down, he got up and moved to sit on our row, two seats away.

‘Look at that man’s dog,’ my son said in loud voice. ‘It’s tiny.’

I glanced across. Both dog and man stared back at me with large unblinking eyes.

‘Wills,’ I said, ‘do you want to play on the iPad?’

He took the gadget from me, unlocked it with the speed of an expert, and began swiping rapidly right and left to slice pieces of electronic fruit tumbling from the top of the screen.

Mel had gone into the interview room first. PC Khan had offered to sit us both down together to save time, but I didn’t want William to hear any of it, so we had agreed to go in separately. She came out after half an hour.

‘Mummy!’ William announced as she re-emerged from the security door beside the front desk. He ran over to her and hugged her around the waist as if he hadn’t seen her for a year. ‘I’m bored. Can we get an ice cream?’

‘It’s too cold for ice cream, William.’

‘How was it?’ I said to her.

She shrugged.

‘I just told him . . . you know. Everything.’

‘You feel OK?’

‘Yes. Weirdly, I feel better for it all being out in the open. I’m actually all right.’

I followed PC Khan through the steel security door and into a small interview room at the back of the station. He was in his early twenties, slightly built, with calm, intelligent eyes. His uniform was immaculate.

‘So, Mr Lynch, you’re a friend of Benjamin Delaney?’

Friend was stretching it somewhat but I nodded anyway.