It was a call from my cousin, Nell, which set me off. She rang to say she’d found my old doll’s house in her attic - she’d inherited it when I’d grown out of it. Not only did had she found the doll’s house, but also a box full of furniture and little people. And yes, the bendy "father" of the house was there, with wool bound round his wiry limbs, and the dressing table with the tiny round bit of glass stuck on.

"Next time you come to stay we’ll play with it together!" she said, jokingly.
But she’d hit on one of the major problems about being an adult. You can’t play with them. I suppose you could, self-consciously, in an earnest therapy group. But every time your teddy hit another person’s stuffed dog, a ponderous counsellor would be on hand to tell you that it signified the rage you felt for your father. Not a hell of a lot of fun.

But is there ever quite so much fun to be had as playing with children? And before you dial 999, let me assure you I mean playing, not playing. Goodies and baddies. Hide and seek. That sort of thing.

A lot of my granny friends clearly do not go in for playing. They love their grandchildren, but beyond a bit of colouring or making biscuits together, they can’t join in the fun. They are quite prepared to go to the park to feed the ducks, and read endless books to them. They will help them collect dried leaves and stick them into a chart and buy them toys galore. But they won’t actually play with them.

But I’m afraid to say I enjoy it. And I say "afraid" because I’m worried I’m a bit weird.

There was nothing I liked more, when my grandchildren were smaller, than pretending the sofa was a boat, and the cushions we’d thrown on the floor were fish. We used a string bag to catch them with and every so often my grandson would dive off onto the carpet to kill a shark, which I would then cook and we’d eat – unless, of course, the shark escaped from the oven, as he so often did and we had to start all over again.

Once we built an entire city out of cardboard boxes on the lawn. There was a prison (his) and an art gallery (mine) and a hospital and a post office, and luckily I took a photograph before a huge monster came down from the sky and destroyed it by jumping up and down on it until it was flattened.

When my son was tiny we used to play dinosaurs in the bath. I’d make my hands into a couple of these creatures, my fingers as legs and my middle finger as their waving heads.

This pair would walk along the edge of the bath making rude remarks, occasionally pushing each other in to the water and constantly demanding hats and coats from my son, who would obligingly cover them in bubbles. My son talked to them as if they were real, in a completely different voice to the one he used to me.

Until they are about six, children do regard their grannies and granddads as huge playmates. And is there anything nicer than hearing: "You be the bad bear, grannie, and I’ll be the good bear." Or "Watch out grannie! He’s coming to eat you up! I’ll save you!"

I once taught in a pre-nursery school and I’ll never forget one little boy painting an elaborate picture of a house. Together we built up a picture of its inhabitants and added a car, a kennel, a dog, until a rich story emerged. Every event was painted to cover the last, but you could still see the faint outlines of the old story underneath. At the very end, he got out some black paint and proceeded to cover the entire picture.

"Why are you doing that?" I said. I’d been looking forward to showing off his
imaginativeness to his mother when she picked him up.

"It’s night-time," he explained, perfectly rationally, "And they’ve all gone to bed."

Playing is like that. Nothing to show for it except a whole treasure trove of memories and laughter. Oh dear. Sentimental old me. Can’t wait to see the doll’s house again, though.