STORIES keep running about unhappy Londoners upping sticks. Droves of them departing for the idyll of the countryside. Decades ago, I also ran. But it was in the other direction. The confines of a country town were left behind and I arrived in the heady anonymity of Camden.

Back when I was a teenager, my friend Angie’s mother had an affair. It was with an “older” man in the neighbouring, larger town who “did her eyelashes”. Angie said she would never speak to her again.

Angie didn’t know what it meant to do someone’s eyelashes, and neither did I. The mystery of it was thrilling. Rather like the secret of Angie’s runaway mother. When I told my family, however, it turned out they knew already. My dad said the man who ran the sweet shop had told him.

That weekend, Angie’s mother herself, an expensive-looking woman in a cream trench mac, walked into the greengrocer’s where I had a new Saturday job. She came over to chat. It was as if in front of the counter there were two people: the one I knew, and the other, gaudier version. I weighed out the potatoes and glanced surreptitiously at her eyelashes, black next to her fair skin, yet mysteriously free of mascara. What had the “older” man done to them?

Her trolley filled up with shopping, she gave me a knowing smile and walked out. I stared after her. In teenage awkwardness, I felt unable to call her back. Steve the manager, filling out betting slips in the side office, peered through the door. Why had she left without paying? He had to get to the bookies but he’d be calling on her later. Her husband was a cuckold, he added. The other assistant agreed. I stared. Were there actually no secrets in my town? Suddenly it felt like a prison. Steve also knew she was my friend’s mother. He accused me of colluding in theft and sacked me. I never told Angie.

When I moved to London, it was to get away from the hemmed in life. But occasionally London itself has been a village.

Ten years after the greengrocer’s, I was walking by the canal in Little Venice. An expensive-looking woman and much younger man were coming in the other direction. Mother and son? But as they approached, it was clear they were a couple. I stopped. Impossible! Angie’s brazen mother! I blinked between present and past, astonished that London, city of secrets, anonymity and subterfuge, could all at once be so small. Should I march up? Demand compensation for the loss of my long-ago job? They moved by arm in arm.

In another instance, last week was open evening for prospective pupils and their parents at the school where I work. Desks displayed books that we teach.

“Hello,” said a voice. “Remember me?”

I turned to see a man in his 30s or thereabouts. I shook my head.

“Yeah, you do,” he said. “At the school down the road. You taught me. You told us it was your first year of teaching. Those were the days,” he grinned. “No technology. I used to come in for the morning paper register, then slide under the gate and go home.’

I started to laugh. Then I remembered I was the teacher.

“But I don’t want my lad doing the same,” he said, looking down at the 11-year-old red head peering curiously up at his dad.

And then I recalled him. A wiry, pastier version of the son now at his side. It was at my first school and indeed in my first year. He winked and went off to inspect the books. The boy lingered.

“Was my dad naughty?” he asked with a smirk.

A mere three days later, I was in a sports shop being measured for a pair of trainers. A male assistant knelt on the floor in front of me. He felt my bare feet for width and precise sizing. I should get one size larger than my usual, he advised, as my feet would probably swell during the long run. I nodded. He continued to feel them, pressing my toes with his fingers. Then, leaning back, he opened a box of trainers. He glanced up. And stopped. I stopped, too. We were back in my classroom, and he was looking up at me through those same, square-framed glasses.

I’d taught him 15 years previously. Now he was a jobbing actor. He didn’t feel my feet again. I tried to forget he ever had. Meeting a former student at an open evening is one thing. Having one grasp your toes three days later is quite another. In such a rollercoaster ride of recognition, whatever would the next encounter be?

But now I find myself studying passers-by. With a new wistfulness, I scan the faces of young adults in crowds, as if looking for children lost or given away. Every so often, a stranger does seem familiar. Did I once know him, briefly? And is London really so anonymous after all? Is anywhere?

Yet even though these moments are like pockets of country life, reminding me of my childhood, I wouldn’t trade the leafy, buzzing streets of north London for anywhere.