‘You should have called the first one Hawthorne Investigates.’

‘That’s not what I mean.’ I snatched one of the KitKats after all. I didn’t want to eat it. I just wanted to spoil the pattern. ‘It’s the concept. It doesn’t work.’

I’d decided that all the titles would have some sort of literary reference. After all, I was a writer; he was a detective. The Word is Murder, The Sentence is Death, A Line to Kill. It had seemed like a good idea at the time, but I’d already run out of grammatical allusions. Life Comes to a Full Stop? It wouldn’t make sense in America, where they have periods. The Case of the Missing Colon? It would only work if a body part went missing from a morgue. No. Even the titles were telling me that I had agreed to a trilogy and that was as far as it would go.

‘You can find someone else,’ I suggested, weakly.

He shrugged. ‘I like working with you, mate. You and I get along … somehow. We’ve got an understanding.’

‘I’m not sure I understand anything,’ I said. It was strange. I hadn’t expected this meeting to become so gloomy. I’d thought it was just going to be a simple parting of the ways. ‘It’s not the end of our relationship,’ I continued. ‘There are two more books still to come out. We’ll meet at the publishers. And maybe there’ll be more literary festivals – although after the last one, people may be nervous about inviting us.’

‘I thought we did all right.’

‘Three people got killed!’

I had never seen Hawthorne so defeated. At that moment, I realised that whatever I might have said, some sort of bond had grown between us. At the end of the day, it’s not possible to investigate the deaths of seven human beings without becoming close. I admired Hawthorne. I liked him and I’d always tried to make him likeable when I was writing about him. Suddenly I wanted to leave.

I didn’t eat the KitKat. I finished my tea and stood up. ‘Look,’ I said. ‘If something comes up, another investigation, let me know and maybe I’ll think again.’ Even as I spoke the words, I knew I wouldn’t. At the same time, I was quite sure he wouldn’t get in touch with me either.

‘I’ll do that,’ he said.

I walked towards the door but before I reached it, I turned back. I wanted to end on a more cheerful note. ‘My play opens next week,’ I said. ‘Why don’t you come to the first night?’

‘What play is that?’

I was sure I’d mentioned it to him. ‘Mindgame. It’s a sort of thriller. It’s got Jordan Williams and Tirian Kirke in it.’ They were both well-known actors but Hawthorne didn’t appear to have heard of either of them. ‘You’ll enjoy it. It’s on at the Vaudeville Theatre.’

‘Where’s that?’

‘It’s in the Strand … opposite the Savoy. There’ll be a party afterwards and Hilda will be there.’