‘Lax,’ agrees Minnie, equally gravely. ‘Lax bax … Guess how much I love you,’ she adds inconsequentially.

I know that Minnie’s quoting from her bedtime book, but Elinor doesn’t – and I’m stunned by her instant reaction. Her cheekbones start to tremble and there’s a sheen to her eye.

‘Well,’ she says in a low voice. ‘Well, Minnie.’

It’s almost unbearable, watching her tight, chalky-white face struggle with emotion. She puts her lined, beringed hand on Minnie’s head and strokes it a few times, as though that’s the most she can bring herself to do.

God, I’d love to loosen her up. I should have ordered the Mind-Altering Tea for Repressed Older Women in Chanel Suits.

‘Elinor, we have to reconcile you with Luke,’ I say impulsively. ‘I want you to be part of the family. Properly. I’m going to stage an intervention at our house and I’m not letting either of you go till you’re friends.’

‘I don’t believe “friends” is the appropriate term,’ she says, looking puzzled. ‘We are mother and son, not contemporaries.’

OK, this is why she doesn’t help herself.

‘Yes it is!’ I say. ‘It’s totally appropriate. I’m friends with my mum and you can jolly well be friends with Luke. When I tell him everything you did for the party—’

‘No.’ Elinor cuts me off, a sudden steel to her voice. ‘I have told you, Rebecca. Luke must never know of my involvement.’

‘But you did such an amazing thing!’ I say in frustration. ‘And he thinks it was Suze and Tarkie! It’s crazy!’

‘He must never know.’

‘But—’

‘He must never know. I am not buying his love,’ she adds, so quietly I can barely hear her.

‘Elinor, it’s not “buying his love”,’ I say gently. ‘It wasn’t just about the money. It was about all the thought and effort you put into it.’

The girl arrives with our drinks, and we’re both silent as she arranges teapots, cups, strainers and little sugar crystals on a trolley made out of bamboo. I pour Elinor her hot water and she picks it up without drinking it.

‘So, Elinor,’ I say, in soft, coaxing tones. ‘Will you tell him?’

‘No,’ she says in final tones. ‘And you will not tell him, either. You made me a promise.’

Argh. It’s like she’s made of granite. This intervention is not going to be an easy matter.

‘OK, then. Well, we’ll find another way.’ I reach in my bag for my ‘conflict resolution’ notes. I printed them off from Google and they’ve been quite helpful, except I realized a bit too late they were about conflict resolution in an industrial-action situation. I skim through the pages, trying to find something useful. Picketing, no … union representation, no … Health and Safety Executive, no … cooperation techniques … ooh, that’s more like it. Win-win negotiating strategy.

Yes! That’s very good. Win-win is exactly what we need. In fact, I’m not sure why anyone would ever choose anything except win-win. I mean, why would you opt for lose-lose?