My mother was an actress and my father an actor. They got married just before the war. He managed to produce myself and my older brother Pieter, but he wasn’t there much. My mother then fell in love with a bloke called Jack Morpurgo. My father came back to London from the war in 1946 and discovered that his place had been taken. He made an extraordinary decision: his feeling was that if my mother wished to live with Jack then he didn’t want to be around like a spare father because he didn’t know us, and he thought it would be an intrusion. So he said, “Fine: I’m absenting myself and you and Jack will bring up my boys.”

My parents divorced and my father emigrated to Canada. I was aware of a tension in the household: no one ever talked about my father because at the time divorce was a shameful thing. What happened was that a pretence was created that we were all one big, happy family — a stepbrother and a stepsister, Pieter and myself, and we were all called Morpurgo. I wasn’t allowed to call my mother Mum or my stepfather Dad: I had to call her Kippe and he was always Jack. We didn’t speak of this removed father. He didn’t exist.

Then when I was 19 I was watching Great Expectations on TV one Christmas evening with the family. In the first scene, up from behind a gravestone rears a hideous convict: Magwitch. My mother was sitting next to me, grabbed my knee and said: “Oh my God, it’s your father.” We didn’t meet until I was in my mid-twenties, by which time I had a better idea of my mother’s relationships. Although always kind and attentive, she wasn’t very tactile. Expressing affection was difficult, and since she was so concerned to keep the affection of my stepfather I think it became a strain to her.

She died in her seventies, my stepfather died four years ago and my father died last year. I had got to know him and an extraordinary relationship built up that was a love between a father and a son but without the baggage of bringing a son up. I think he liked that: he could see me for what I was, and I could see how he was as a man, not just as a father. He wanted his ashes to be split between a beach in Bermuda where he’d gone for walks with his second wife, and my garden in Devon, as this is where my mother’s ashes are. He never expressed it, but his love for my mother had never left him.

With my own marriage it became the most important thing to have a relationship that was solid. I got married stupidly young — Clare had lived a lot longer than I had in terms of maturity. She was the first person who made me think as an adult, so I went to university and became a teacher and we had three children very young — two boys and an adopted girl.

I don’t think you have any objectivity when you’re 20, 21. You’re so busy growing yourself that you can’t stand back. While I don’t think that I was a terrible father, I don’t think I gave enough of myself.

I’m more at ease and less anxious dealing with my grandchildren. We do ridiculous things like rolling down fields. I become a bit childlike again, which is a wonderful enrichment. I feel more equal to them than I ever did with my children when they were young, and I think it is because there is both deep affection and a certain detachment.

Michael Morpurgo appears at the Hay Fever Festival on May 29, 30, and June 1

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