Last week, I went out in the broiling heat, and in the lift down to the tube, stood opposite two young men in sandals. I couldn't help but notice that they had fabulous toes: straight, evenly spaced, perfectly formed toenails and most surprising, all spotlessly clean. How did they manage it? If I go out in my sandals my toes will be covered in grime within minutes, and they look nothing like the toes in the lift. Mine overlap, and the smaller they are, the less toe-shaped they become. If you saw the smallest ones out of context, you would never think "a toe!" but instead "a shiny red or sallow mini-ball stuck with an oddly-shaped talon." Elephant hide is a baby's bottom compared with the soles of my feet.

My fault, I suppose, because my toes are nearly 70 years old, I've failed to look after them properly, swanked about barefoot in the 60s, and now my sins have come home to rot. And so have Fielding's. But his toes are rather damp and pallid, like something you've discovered in your basement, and he too has yellow dagger toenails, which he tries to attend to, but can't see properly from a distance, and can't stoop to cut them, because his back is no longer bendy enough, so sandals are not an option for him.

And that's only the toes. His feet are a blotchy red, and as we work our way up, there's worse to come. When I started writing about old age 18 years ago, the bottom of my thighs were beginning to hang over my knees, and this trend is ongoing. In those days Rosemary's ankle had only just broken and is still mouldering, but she has forbidden me to describe it. "Sometimes," says she strictly, "your desire to be vulgar overwhelms you. Please let's not go any higher." But she allowed a comparison of legs. And clearly mine are the least ghastly.

So I went into the garden in shorts and bare feet, and trod straight in something nasty in the long grass. It's a tough world.