For the next hour or so Mum talked about the chiropractor she’d been seeing and the next holiday she was going on with the sculptor boyfriend and the politics of the houseboat community, and I managed to avoid giving away any more about what Mark and I were planning. Then Mum accompanied me up to the gangplank and we said goodbye.

‘Be careful, won’t you? Watch your step,’ she called out as I set off towards the riverbank, followed by some other warning I couldn’t quite hear.

I turned and smiled and waved and said, ‘Don’t worry, I will.’

It was a relief to get back onto firm dry land. I waved again and set off towards the tube, and it wasn’t until about half an hour later, when I was somewhere in a Northern Line tunnel, that I figured out what she’d said: Don’t let Ingrid bully you. Or Mark, either.

It had always been obvious that Ingrid adored Mark, but she was more the intimidating kind of doting mother than the gushing kind. She tolerated me, but this was strictly conditional. If she ever thought I was letting Mark down, in however trivial a way, I found myself bathed in disapproval.

When we showed up on her doorstep for Sunday lunch the following weekend, her opening gambit was to embrace Mark, then hold him at arm’s length and look him up and down before pronouncing judgement: ‘You look pale. Isn’t your wife feeding you properly?’

She released him and turned towards me; I kissed her drily on the cheek. In terms of personal style Ingrid was Mum’s polar opposite, with her pearls and collars and pleats and knife-edge ironed-in creases. But she shared Mum’s uncanny knack for highlighting my shortcomings.

‘I don’t think it’s my job to feed him,’ I said. ‘He’s perfectly capable of feeding himself.’

‘You modern wives don’t think it’s your job to do anything, but you still expect your husbands to change the light bulbs and put the bins out,’ Ingrid retorted.

She ushered us in and took our coats and offered us drinks, and Mark and I perched side by side on her overstuffed sofa and made small talk about the weather and the traffic, which she didn’t seem to find any more interesting than we did – though she made less of an effort to pretend otherwise. After a while, with the air of one who is discharging an unpleasant duty, she set about changing the subject.

‘Do you remember me telling you about the paintings I was asked for, Mark? The ones they want for that collection in London? I’ve left them out in the spare room so you can have a look. I have to say, though, I’m not sure quite why you’re interested. Or why anybody would be, come to that.’

‘I suppose it seems poignant. Given that it’s all that’s left,’ Mark said, putting down his empty sherry glass. I’d had sparkling water, but as I was driving back that wasn’t much of a giveaway.