Mel and I have both turned fifty and we are therefore invisible except in the technical sense to, say, the young waiter who took our order. He was nice-looking, brown-skinned, with black hair slicked straight back from his face. I could see him stepping around the female trio and exchanging eye contact as he slipped them their starters. He said something that was evidently cheeky and they all laughed.

I don’t remember anyone mentioning the fact to me when I was as young as Lola, but you don’t feel yourself growing older. You reach an age – which probably varies according to your history and personal circumstances, but in my case was twenty-seven – and there you are, fully formed. As time passes you note your failures and allow yourself to appreciate what you have done well, but there remains the inner individual who isn’t aware of alteration either mental or physical. Inside my skin, a millimetre or so beneath the eroding surface, I remain twenty-seven years old. It’s a shock, when riding the escalator in Selfridges or somewhere, to confront an unexpected mirror and be obliged to check the discrepancy.

We’ve talked about this, of course, Mel and I. Being invisible to waiters and white-van drivers and brickies doesn’t bother us. What is alarming is the possibility that when we do start to feel our age, it might all happen at once. What if we go from being twenty-seven to being sixty-seven in a day, suddenly getting infirm knees and crochet shawls and a fondness for Book at Bedtime, crumbling away into old ladies as the light falls on us like Rider Haggard’s She?

‘That will be scarier than Alien,’ Mel said.

Joking about our worries is something we have always been able to do together. What else should we do?

I lifted my glass of wine again. ‘Here’s to now,’ I said.

Being old hasn’t happened yet, that’s what the toast means, in spite of the escalator mirror’s warning and in spite of our awareness that it will, that it must.

‘To now,’ Mel echoed happily.

The waiter came with our food. He put Mel’s dish of scallops down in front of her and she immediately picked up her fork to take a mouthful. I had chosen mezzalune di melanzane, half-moons of ravioli stuffed with aubergine. We sampled our own portions and then traded forkfuls. Mel chewed attentively and pronounced my ravioli to be drab, and I agreed with her.

‘Go on,’ I said.

We had started talking about Adrian and I was watching her face as she relayed her concerns. I also wanted to enjoy the restaurant’s brightness and the sweet damp night outside, and the animated faces of the three women and the way the waiter’s long white apron tucked round his waist just so, by listening for a while longer instead of talking.