“Hello Mr Kent. I bet you don’t remember who I am.”

I’d gone to Guy’s Hospital in London for a blood test and the pretty young phlebotomist had recognised me. It was Jolene, who had attended my primary school years ago. A bright, lively child, she’d starred in several of the musicals I’d written and she talked about them with enormous enthusiasm. After a thoroughly enjoyable 20 minutes, I suggested she’d better get on with taking my blood or I’d be blamed for holding the queue of patients up.

It’s always a pleasure when past students or their parents recognise you, smile warmly and tell you what a good education your school offered. When I was a school leader, shopping in the supermarket often took longer than planned because parents would stop to say hello. I remember meeting Naomi’s mum, who told me proudly that her daughter had been accepted into the University of Oxford. I was thrilled. On the other hand, when I spotted Cameron and his awful mother I headed for another aisle. Cameron was a challenging, hyperactive boy and I hurried to the one place in the shop I knew they wouldn’t visit: the fresh fruit and vegetable section.

But the ex-student I remember most vividly is Muhammed. He was in his final year when I joined the school and I was warned that I’d probably have to exclude him. Within days, I discovered that nothing was safe when he was in the vicinity unless it was nailed down. He also irritated his classmates with consummate skill, causing arguments that degenerated into utter chaos, at which point, like Macavity, Muhammed wasn’t there.

But we had to get through the year, and I suggested giving him a leading role in my Christmas play. This occupied him for several hours a week but gave me undeniable grief. He constantly rewrote his part. He’d take himself off to the stockroom and use copious amounts of expensive card to create intricate props. He’d persuade teaching assistants that I had said he could stay in at lunchtime to rehearse. Then chocolate bars would disappear from lunch boxes. Finally, the cast rebelled and said they didn’t want to be in the play until I’d sorted Muhammed out.

Time passed and somehow we reached the end of the year; Muhammed moved on. Seven years later, a smart young man appeared at my office door. It was Muhammed. He told me how well he was doing - he’d almost finished a course in business and was going into partnership with a friend. Four years later, he appeared again, in a smart suit and carrying a very expensive briefcase. His business was successful, he was marrying soon and he hoped he could put his children in our school as it had given him such a good start in life. I had difficulty keeping a straight face.

And then, thumbing through a newspaper a year later, I stopped at a photograph of a young man wanted for a string of daring robberies from hotels in London’s Mayfair. He was always immaculately dressed, the article said, and carried an expensive briefcase.

Mike Kent is a retired primary school headteacher in England. Email: mikejkent@aol.com