I'm suspicious of people who say they were happy at school. I always felt a day prisoner in an institution for improvement. To say I was happy would be to rewrite history. I was as unhappy as any boy aged 13 to 17 could be, cooped up all day being taught things.

I look back on my schooldays as a time of anxiety and lack of freedom, but also of intellectual development. Glasgow Academy, where I attended both primary and second level, was an independent school which had none of the snobbery of English public schools. Although maths were highly valued, the school's English and history teachers were inspirational.

The school was very good at coping with adolescent frustration. The deputy rector, Jock Carruthers, had a brilliant understanding of schoolboys. He understood very well that adolescent revolt had to be contained without our being aware of it.

I was the classic swot but had the satisfaction of believing that I was a rebel. The school venerated rugby above all other activities - you only had to be interested in theatre, for example, to appear rebellious.

We were expected to join the cadet force. In the mornings, we read Wilfred Owen and in the afternoons marched around the playground playing soldiers - it was insane. I deserted from the cadets and, in the process, lost my entire uniform - which I had carefully hidden. I was forced to confess. Another school would have treated me harshly, but apart from being made to clean out a few loos, I was allowed to do community service instead.

I owe a huge debt to my teachers and to Ronnie Woods in particular. But for him I would not have become an historian. In his classes there was no limit to what you could read. It was an intellectual liberation. He encouraged a sense that history was an individual quest for truth and not just something you had to learn. You could study things that mattered in an independent way, instead of being handed a text book and told learn it.

The Glasgow Academy was dedicated as a war memorial in 1925 because so many former pupils had been killed in the First World War. I was preoccupied by the War. My first history project, at the age of 12, was about trench warfare.

After school, I went to Magdalen College, Oxford, to study history. It was wonderful and I'm still there, although in between times, I studied in Germany and spent three years in Cambridge.

I'm an economic and financial historian, but since my schooldays the war has been my constant preoccupation. I worked on it again in my undergraduate years and at Cambridge. It was a sideline waiting to become mainlined.

In E&L on December 8, Gerard Whelan was incorrectly quoted as saying that his son attended the Lucan Educate Together School. In fact, his son attends his local school in Clondalkin, where he is very happy. We also regret that a wrong surname was used in the headline