He had just heard that I had been offered a place at Oxford University and was astounded that someone from his world could cross over to that other place. It was an impossible leap for him to contemplate.
He was a boy in the third year of secondary school. I was a prefect and he had become one of my charges for the year. My job was to supervise his class during registration.
I enjoyed my brief times with these pupils. They were very lippy and they messed around. Their banter was a welcome break from my earnest studying and they challenged my ideas.
But my times with them were rare. I was not in school much then - I was focused on escaping from my grim Welsh valleys town. The escape plan centred around getting a place at Oxford to read English - but even some teachers thought this scheme over-ambitious.
So instead I would slip home to read books that were not on my A-level English course, becoming an expert on Thomas Hardy novels. I read them all, relishing the blighted lives of Tess of the D'Urbervilles and Jude, too obscure to win a place at Christminster, Hardy's name for Oxford. But no Hardy novel was too obscure for me - I had read them all by the age of 17.
The strategy paid off - when I was offered my university place, my "impressive" (if absurd) reading was commended. A tutor was later to put this so-called achievement into perspective when he commented: "It doesn't matter that Horner has read everything, because she can't remember any of it."
Well, maybe I should have listened to that 13-year-old boy. I would love to know what he would say about it all now. It would be nice to ask him to justify being so unambitious at 13.
At the time his attitude seemed natural - after all, our home town had one of the highest male unemployment rates in the country. But the statistics did not bother me. I had been given a different outlook on life. My parents, both teachers, spoke gratefully of the Welsh grammar schools which had rescued them from working in their parents' shops (in fact my mother had attended the same school as I did before it became a comprehensive, but it had a very different atmosphere then).
I was also lucky to have been taught Latin (in the last years before the subject was declared out of bounds) by an amazing teacher. On the day he first strode into school, sweeping past us in a floor-length black coat, it was as if he had stepped out of the tale of the Pied Piper of Hamlyn. As we watched him in the playground we were mesmerised and a little bit freaked out. Did he know how uncool he was? Did he care?
Later, in his lessons, he urged us to read books we did not have to know about to pass exams, and to be enthusiastic about learning. Was he mad? Did he want us to be slaughtered at break times?
If he did know, he did not care, and he helped me to discover that I did not care either. He freed me from trying to please people who just wanted me to be as trapped as they were. So I forgot about them - and I had Tess and Jude for company until I made real friends at university.
That was all 20 years ago, but it suddenly seems horribly current again. An invitation to a reunion of my old classmates lurks in my email inbox. As I was debating whether to go or not, my eyes fell on my old school's Estyn report. The Welsh inspectors found the place has a good ethos now and is very successful. It was good to see that, especially as in the same issue of The TES we carried a study that shows that despite all the egalitarian talk, middle-class children still have the best chance of getting to university.
Maybe in 20 years' time The TES will be reporting that tough, bright working-class kids are edging out ones from leafy boroughs. Then perhaps cheeky 13-year-olds in grim Welsh towns will not believe they are too thick to have a future.
Anne Horner is deputy chief sub-editor of The TES