Thomas is our cat. We got him – can it be? – in 1999. He was four then, so some rudimentary arithmetic suggests that he's 15 years old, which is about a hundred and fifty in cat years. Or people years – however that works. Anyway, he's old.

He's starting to show his age, in a variety of ways. He's very, very thin, and his fur is dull. He smells a bit peculiar. He has become strangely affectionate; he'll hang around when you're in the kitchen, stretching up and wrapping his arms around your legs. He also comes around when we're eating and reaches up to gently paw Delphine or I on the side. Today I picked him up and he settled uncomfortably on my lap for a few minutes – he wants to be near us but he's not sure how to enjoy it when it happens. He's never been a lap cat before.

At fifteen years, and so obviously fading, we know Thomas isn't going to be with us for long. I don't know how he's going to go. I suppose he'll get more and more infirm until he can't manage any more and we take him to the vet to have some of that alarmingly purple liquid injected into him. Or maybe we'll just come downstairs one morning and he'll be dead. I just hope it isn't messy or painful.