There was one wall that made me especially uneasy and I saw it every day on the way to school. It ended at the corner where I crossed the main road so there was no need to walk beside it, but sometimes, going into town, we took that route. The pavement was very narrow there. Walking along it I would look up at the wall. It seemed impossibly high, as high as a house, because I was so close to the foot of it, and it was completely featureless, course after course of dark red brick. I felt that whatever lay behind it must be deeply unfriendly or threatening. I lived only a few hundred metres away from it, but the streets in between were ordinary little terraced houses with low garden fences and hedges. No one I knew lived behind high walls.

I was playing in the street one day with my friend Elizabeth when she said suddenly, “Let’s go and see the tortoise lady.”

“Who’s the tortoise lady?” I was already picturing someone bleary-eyed and wrinkled, head swaying from side to side on stringy neck.

“Mrs Bentley. She’s a friend of ours. She won’t mind,” Elizabeth said airily. “She’s got tortoises.”

In those days it was not illegal to import tortoises and they were popular pets. I had one myself and I didn’t see why Mrs Bentley’s tortoises would be any more exciting than mine. I was also shy about calling uninvited on a total stranger. When people said. “Oh, so-and-so won’t mind”, they were usually wrong.

It was not far to Mrs Bentley’s. She lived in one of the tall dark-red-brick houses in the lane that led to our school. There was a fence with a hedge above it bordering the lane, then a glassed-in porch with steps up to it. It was not the kind of place that I was used to visiting, but Elizabeth’s family were a lot better off than mine. I hung back while she went confidently up the steps and rang the bell.

The door was opened by an old lady. She leaned on a stick and she was wrinkled, but she looked nothing like a tortoise.

“Good afternoon, Mrs Bentley,” Elizabeth said, in the way you did then.

“I’ve brought my friend to see the tortoises.”

Mrs Bentley didn’t mind a bit. She invited us in and we saw the tortoises - all 20 of them. Mrs Bentley didn’t just have tortoises, she bred them. The mother and grandmother of all the others was Mary, who was the size of a hub cap. The youngest was Eustace, only a few months out of his egg. Mary and her family lived in the garden but Mrs Bentley took us up to the attic to meet Eustace who was kept in a special box near the hot-water tank because he was so small. Mary was impressive but baby Eustace, not much bigger than a 50-pence piece, was astonishing.

Before we left we went back to the garden to say goodbye to the others.

They were all ambling about on a long green lawn and at the end of the lawn was a flower bed with bushes growing against a high brick wall...

Everything fell into place; I knew where I was. The wall I hated so much and tried to avoid passing was Mrs Bentley’s garden wall. It didn’t look nearly so high from this side and not at all menacing. It never looked menacing again. Now when I saw it I remembered what was on the other side: the green garden, the lawn, Mrs Bentley and her tortoises.

I met her only once after that. I don’t think she remembered who I was even when I asked after Eustace. Mary was still going strong, she said, but Eustace had died. She seemed sorry but not terribly sad. Eustace had been so small and frail, perhaps she had not expected him to live. Mary, of course, was a tough old thing. She may still be alive to this day.

I often set my stories in that town where I grew up but I never name it. No one who knows it now would recognise the place I write about, which is the town I remember. I lived there for 12 years and now I can’t find my way around the place. Our house is under the ring road, which passes a supermarket on the corner of North Street where I used to cross the road to go to school. The supermarket stands where Mrs Bentley had her house and garden.

The wall has gone too. I miss it now. It was a beautiful piece of brickwork.