Mr Lavelle was the senior classics master at Holyrood School, Glasgow, a co-educational Catholic senior secondary school with 1,200 pupils to which my three sisters and I all went. His name was John but he was always known as Friend Lavelle because he used the term “friend” when addressing pupils. The tradition was that girls were called by first names and boys by their surnames. Mr Lavelle was the only teacher who avoided impersonal surnames and called the boys Friend. He was a wonderful teacher and I suspect he had a great influence on many others as well as me.

Mr Lavelle made me feel special. I was only in my first or second year when he picked me for a school team taking part in a new Scottish television programme, a sort of cross between Top of the Form and University Challenge. I was flattered. Being chosen is always a great means of inspiring a child’s loyalty. We got through to the second stage of the finals.

I had no personal experience of Mr Lavelle as a teacher at this stage, but I knew him because he had taught my elder sisters and occasionally he would meet my father in the pub. My father was rather bookish although he was unskilled. He worked as a bundle strangler (a dispatch hand) on the Glasgow Daily Record.

I was a confident child, I think, because I had such a devoted and loving father. He was very involved with my upbringing and very keen on education. Mr Lavelle was about my father’s age, or a little older. He had wavy, sandy-coloured hair, going grey, a lined face and twinkly eyes.

I really enjoyed learning Latin and, when I was in my third year, because I liked Mr Lavelle so much, I asked him if I might start doing Greek. He was thrilled because very few others were interested. I explained that what appealed to me about Latin was that it was like a puzzle. I remember him saying that classical Greek was even more of a puzzle!

I was the only one in my year studying Greek and Mr Lavelle juggled the timetable to fit in lessons instead of PE and sewing and other classes I wasn’t too interested in. We became very, very good friends.

Part of his skill was that he made lessons interesting. He was never patronising, never had to raise his voice. He always wore a gown and sometimes he twirled his sleeve as he talked. He would walk up and down with his hands behind his back and say: “Let’s be hearing from you Friend.” He could be strict. If you didn’t do your homework, he’d set twice as much next time.

Because I felt special and wanted to please him, I worked hard. My solo Greek lessons with Mr Lavelle were like private tutorials. We discussed how classical stories affected our view of war and the way mythology from the classics feeds into today’s literature.

Mr Lavelle ran the school debating society and encouraged me to get involved from the age of 14 or 15, even though the others taking part were sixth-formers. He taught me how to build up an argument and how to look at things from both sides. I soon began to love debating and took part in inter-school competitions. It was a great grounding for someone going to the Bar.

Part of the Scottish education system is based on the idea of the democratic intellect, that children should be taught to question things and be told that their view is as valuable as anybody else’s. My fear is that there isn’t enough time in the curriculum any more, particularly in the state system, for things like debating.

In recent years I have been a judge in The Observer Mace competition and one of the disappointing things is that independent sector schools are incredibly good at debating but you rarely see state system pupils as confident and skilled. I believe strongly in the importance of learning how to debate. It is essential in encouraging young people to think and to engage with issues. I’d like to see debating given emphasis in the state school system. And I want to say to all the lawyers I know: “Go into your local state school and offer to give them time, help them to get a debating society going.”

I talked about my future with Mr Lavelle and my first plan was to take an English degree. I had a place at Glasgow University but at the last minute came to England and went to the Council of Legal Education, the Inns of Court School of Law and then the Bar.

Mr Lavelle approved of that. He was rather pleased that I’d decided to do what he felt I should have done all along.

I went back to see him after I’d left school and although I thanked him for his help, I don’t think I expressed to him clearly enough how influential he was in my life. Many years later, after I’d presented Heart of the Matter on television, he wrote to me. By that time he was very ill and his handwriting was very shaky. He said in the letter that he always thought of me as his Portia.

Helena Kennedy QC practises criminal law and is a broadcaster on law and women’s rights. She is chancellor of Oxford Brookes University, chairman of Charter 88, a council member of the Howard League for Penal Reform and chairman of the Widening Participation Committee for the Further Education Funding Council. She is 46, married and has three children.