‘Peter,’ said Tyburn. ‘I need you to stop just pretending to be clever and actually be clever. Of course I knew it, intellectually – Mum’s looked basically the same since I can remember, and there’s Father Thames who doesn’t look a day over a thousand. But that’s not the same as staring it in the face.’ She shook her head.

I nodded my understanding, but she wasn’t convinced.

‘So when we came back to London I sort of let myself fall back into middle age.’

‘Just like that?’

‘Well, I stayed away from mirrors and watched a lot of Antiques Roadshow – that helped.’

‘How quickly did it happen?’ I asked.

‘A couple of months,’ she said. ‘Crow’s feet, fat thighs and all.’

Fairly unobtrusive crow’s feet, I thought.

‘And it all just reverted?’

Lady Ty shrugged.

‘I may have left out the stretch marks,’ she said

‘Did he notice?’

‘I don’t know,’ she said. ‘When you’re married you get used to each other – you really only see the person you expect to see.’

‘Can Beverley make herself look older?’ I asked, and then I thought of her sister Nicky who was allegedly nine years old and might just have drowned a man on dry land. ‘Can Nicky?’

‘There’s no manual, Peter,’ said Lady Ty. ‘There’s no self-help group with a Tumblr page and an easy-to-access FAQ. And I’m the oldest, which means everything happens to me first – of course. I have to make all the mistakes, and my first one was thinking I was human and could have a human life.’

I felt a cold clutching in my chest. It must have shown on my face.

‘I’m going to outlive my babies, Peter,’ she said. ‘I’m going to outlive my babies’ babies. Barring some radically unforeseen circumstance I’m going to outlive everyone I love, except my family.’ She made a strange head bob. ‘I want to save my sister some pain – so sue me.’

I didn’t know what to say, so I didn’t say anything.

‘Are you at least going to think about what I’ve said?’

‘Who stabbed the sniper?’ I asked. ‘Do you know?’

Lady Ty stiffened and she took another sip of her wine before answering with a question. ‘Do you have any theories?’ she asked.

‘I think it was Sir William Tyburn, late of this parish,’ I said. ‘Do you know who I’m talking about?’

‘The son of old Father Thames,’ she spoke the phrase in a formal manner, as if invoking a spirit or introducing a judge.

I waited, but she sipped more wine and looked at me over the rim of her glass.

‘Was it him?’

Lady Ty shrugged.

‘Is he associated with you in some way?’ I asked. ‘At a spiritual level?’

Lady Ty snorted into her wine, put the glass down and quickly covered her nose and mouth with her hand.