My earliest memory is the birth of my brother. I was six. I’d had an operation on the kitchen table for an absess in my ear, so I’d been put out with anaesthetic. My mother had given birth in her bedroom. When I woke, my nanny said, “Do you want to see your little brother?” I said, “No, I want a banana.” I was motivated by food even then.

Nobody thought a white girl should learn to cook in South Africa. I went to drama school. My mother was an actress, so I thought I’d be an actress. I liked the theatre. Then, I thought: “I’m not very good at this.” So, I went to art school thinking I’d do stage design. I was told firmly, by the head, I was never going to make it.

My greatest achievement has been to put a sculpture on the fourth plinth in Trafalgar Square. I had the idea and it took five years and 13 committees… But I won in the end. I love the sculpture of the bull there now – a replica of one destroyed by Isis in Syria. It’s made of empty date-syrup tins. The Syrian date industry was ruined by war, too.

I remarried three years ago. I met John when I was 70. I can’t say the secret to a happy marriage is having separate homes any longer as we’re building a house together. We always slept together in the same house, but the joy is all his clobber lives in his house. We have to have a big clear out. It’s going to be horrific.

My worst habit is opening the fridge and thinking: “I’d like to eat something.”

Bake Off has been a renaissance for me. I turn up, taste something and get paid rather well. What could be nicer? You don’t make many new deep friendships at our age, but Sandi [Toksvig] will be a friend until I die. I’d be very surprised if I didn’t stay in touch with Paul [Hollywood] and Noel [Fielding].

I’m an optimist – very glass half-full. People are critical of those who are depressed and that’s quite wrong. It’s about levels of serotonin in the brain. I must have the right mix. If things go wrong, I’m upset for a bit, then think: “Shall I have another go?” or “Move on.” I have a more positive, forward-looking attitude than a lot of people. And that’s just luck.

Prue Leith judges The Great British Bake Off on Channel 4 on Tuesdays at 8pm