Officially he taught me geography, but actually, he taught me some of the best lessons I have learnt. The first was not just the most difficult but also the most revealing of myself.

In the 1960s, Doon valued its sportsmen far more than scholars. This meant that a child who had never swung a cricket bat nor kicked a football was at a significant disadvantage. My talents lay in acting and debating and, yes, cramming too. But these were looked down upon.

Guru, however, would find ways of making artistic talents feel better than sporting achievements. He would recall clever sentences from my debates – and I could sense this was praise – or a dramatic posture I struck on stage; and though he was gently taking the mickey, he was also conveying how attentive he’d been, and make me feel special. In his estimation, this was sufficient reason to make me house captain in my last year, even though the best I’d achieved at sport was Juniors III in cricket. On the one solitary occasion the ball had come in my direction, presenting me a sitting catch, I dropped it.

Guru thus gave me the confidence Doon School would never have imparted on its own. He helped me grow up, become aware of my limitations as much as my talents and to handle setbacks, mistakes and failures. He taught me to pick myself up and go on. A necessary lesson, because I often stumbled and fell.

Years later, when I was an adult, I recalled another lesson from Guru. Punishment is not necessarily the best response when someone has erred. There are times when overlooking the error is better.

Many are the times when Guru practised this principle. It covered instances of blatant naughtiness to crafty lying to foolish but wilful pranks. He was always aware of my mistakes but overlooked them. Yet from the expression on his face, I knew he expected better. Even as a teenager, that made me feel bad. More than anything else, I wanted to be in his best books. His disapproval was, therefore, crushing. Guru knew that was punishment enough.

I try to remember this lesson when others make mistakes, but it isn’t easy. It requires wisdom and restraint. Guru had both. I often have neither. This is a lesson I haven’t properly learnt.

The third lesson, I’m glad to say, I do practise. It’s a simple one. A little bit of etiquette makes a significant difference to the impression you leave behind. Greet people when you enter a room and never forget “please” and “thank you”.

I don’t think Guru ever explicitly told me to do this but, then, his example was always there for everyone to see. So careful was his cultivation of good manners and so high the regard in which we held him, that simply by emulating his example, these graces became a habit for the rest of us. I learnt by imitation.

As I look back on my life, Guru’s imprint is unmistakable. I don’t know if the Battle of Waterloo was won on the playing fields of Eton, but certainly the man in me was shaped by the house master of Jaipur House. That’s why he will always be my guru.

Karan Thapar is the author of Devil’s Advocate: The Untold Story The views expressed are personal