‘An excellent question, my dear. He tells me he’s in venture finance. I gather that’s code for taking very large bets with other people’s money. Am I proud of him? Of course I am. Can he be insufferably rude on occasions? I’m afraid so. My only excuse is that he left home at a tender age. Carting him round the world from posting to posting simply wasn’t an option. I’m not sure he took to prep school and in various ways he’s been paying me back ever since. Guilt, I’m afraid, is harder to bear the older you get, but one day we might be kinder to each other.’

Kinder to each other. I’ve been here before and I sense that Sir William understands that. By now, after a couple of hours of conversation, I know exactly what has drawn Christianne to this man. He’s fluent in a number of languages. He’s shrewd, witty, effortlessly charming, and a brilliant listener. Not once has he given us the impression that he might be anyone special. His knighthood, perhaps like his wayward son, was simply an inexplicable accident that happened en route.

We say our goodbyes in the late afternoon. Sir William kisses me on both cheeks, warms my hands in his, and insists I’m welcome any time. When I tell him I have to go back to London, he looks pained.

‘Our loss, my dear,’ he says. ‘God speed.’

Christianne and I dawdle on the way home. She tells me she’s tired, and when I suggest a pause at a pub called The Feathers in the High Street, she’s very happy to say yes. Two large glasses of Merlot arrive, and when I propose a toast, I notice her hand shaking with the effort of holding the glass. I know she wants me to stay a couple of days more, and in truth I’d like to, but a number of pressing engagements await me in London, and I know I have to get back on the road. When I ask the barman for a pen and a sheet of paper, and write down my contact details, she studies them carefully.

‘W11?’ she queries.

‘Holland Park. Come and stay any time. You’d like it.’

‘You mean that?’

‘I do.’

‘Both of us? Andy, too?’

I say nothing and hold her gaze for a long moment before she finally says she understands.

‘It’s nothing personal.’ I put my hand over hers. ‘Nothing to do with Andy. It’s just that this, just the pair of us, works so well.’

‘You mean that?’ she says again.

‘Yes.’

Over the wine, we talk a little more about our afternoon with Sir William. When I tell her the man was an utter delight, I mean it, but I’m curious to know about his private life. Was there a Lady Penny?

‘Yes.’

‘And?’