Perhaps I should call him Bill. That is not his real name of course, but as he is a prisoner as a guest of Her Majesty it is as well that he should remain anonymous. He is real enough though and I have known him for more than 30 years, since he was in my physics group at the boys’ grammar school where I was head of the science department.

So let’s turn back the years. Bill was keen on the sciences to the extent that he would come along to the laboratories area at break time or lunch time if I was there catching up on my marking, either to select a book from my library which I was building up or just look at any ongoing experiments. He would boast of a singing voice which would give a perfect sine wave at various frequencies and he enjoyed demonstrating this by means of the oscilloscope and microphone.

I did not discourage his visits, a young scientist in the making I thought. Of course, this was before the days when paedophilia and child abuse were regularly reported in the press. Now I would not have dared to be alone with a pupil. But that was 30 years ago when the nurturing of a young lad’s latent talent seemed more important than possible danger signals.

Bill eventually did his O-levels, eschewed A-levels to my disappointment, left school and got himself a job. Little did I know that he would re-enter my life in a few short years. Some time in the early 1980s a letter arrived at school on prison notepaper addressed to me. The London postmark gave no clue. Bill, then aged 22, wanted to let me know that he was incarcerated in Wormwood Scrubs and that he expected to be there for some time.

Having been a Home Office accredited prison visitor for several years, I decided to pay him a visit. The journey from Yorkshire was long but allowed me to reach him in time to spend an hour recalling past times. He seemed grateful for my visit and, sympathetically, I offered to call and see him again. Which I did, over the next two decades in Armley Jail, Wakefield Prison and now at his present secure residence in the north of England.

The years passed. I retired. Bill’s hair began to show flecks of grey, then he began to complain of aches and pains as he neared his mid 40s. My own arthritis started years before yet still I turn up, every three months now, as the long return journey by car across the Pennines is not an easy one. But there is no one else so I cannot let him down. After all, the relationship between a teacher and a pupil goes back to the time of Pythagoras and I suppose it holds true for ex pupils, too.

His present score behind bars is 25 years. Twenty five years since he stood in the dock at number one court in The Old Bailey and pleaded guilty. But to this day I have not any knowledge of guilty to what. It is an unwritten law that when visiting a prisoner one never asks about his crime. If he tells you and wants to talk about it then that is fine. But never ask. And now, 25 years later, I still do not know the reason for his lengthy detention.

So the routine continues. Every three months I submit to a search at the prison entrance, walk through the electronic security gate, which these days now bleeps due to the metal in my replacement knee, and am escorted through six locked doors to reach the visitors’ room where, over a cup of prison tea, we share again the reminiscences of those early years at school.

A good brain, he discusses the affairs of the world even though he is largely shielded from it. He is learning Japanese, though whether he will ever achieve his ambition to visit Tokyo is doubtful. Endlessly working towards parole, he describes his next step along this road and retains hope in spite of a series of rejections every few years. Whoever coined the expression “hope springs eternal in the human breast” certainly knew what he was talking about.

I have lost count of the number of visits we have had. And to supplement these, Bill is allowed to use some of his meagre income on telephone calls to me. We discuss the clues from the Saturday Daily Telegraph crossword puzzle.

Over the years he has developed a skill in pottery by working in the prison workshops. Delicate articles, bowls, teapots, and mugs. He has entered some of this work in the Koestler Award competition for works of art created in prisons. He is not afraid to experiment in this work and he is now something of an authority in this field. Each Christmas another item arrives from Bill to add to my collection. In return, I send batteries, the latest Argos catalogue, postcards and other allowable articles.

He has made his plans for release. Long-term planning you might think. He hopes eventually to transfer to an intermediate holding hostel and then to be granted release on parole miles away. I doubt I will see him then. And at the present rate of movement I dare say his “score” behind bars will be at least 30 years. One would be forgiven for thinking what an awful waste of a life this has so far been.

During my long career there has been a legion of young men through my hands. Now doctors, surgeons, bridgebuilders, vets, geologists, mathematicians, an author, engineers and even, I regret to say, a few bankers (only joking). Many still keep in touch and it is always a great pleasure to hear of their doings. And among this list there is a prisoner, a man who has not seen the outside world since, well, since the Falklands War. He is welcome to join my alumni list

Lynden Flint is a retired teacher

Share your story

Have you had a pupil who has affected your life in some way? Tell us about it at features@tes.co.uk.