This much I know: David Suchet, actor, 79

Until the age of seven, I was the spoiled youngest child. I grew up in Baker Street not long after the war, and London was a bomb site. Then my brother arrived on the scene.

Being sent to boarding school in 1954 was confusing. I was homesick for a long time. I was never angry with my parents for sending me away. But I was always curious as to why.

Acting is an insecure life. You’re always worrying about what will come next, and the pressure of being judged I find difficult. Some actors don’t care about criticism and never read reviews. I’m not one of them.

My brother, John, thought Poirot was a buffoon and advised me not to touch the role with a barge pole. I’m very grateful I disagreed – he’s since eaten humble pie.

I’ve never been very good at being complimentary about myself. I’ve never seen myself as a romantic, leading man, but a character performer.

I wouldn’t have succeeded without my wife Sheila. Next year will be our 50th anniversary. The secret of our marriage’s longevity is laughter.

My Poirot moustache was a prop. I couldn’t keep my own facial hair in shape all day, and if I’d had it away from filming, I couldn’t have walked anywhere or had a private life.

I still carry parenting guilt. For the most part of the 25 years, I was filming during the summer and never able to give my family proper holidays. I can’t beat myself up too much, but I do regret it.

Fans aren’t a nuisance – they're your audience, so I’m polite. But I was caught out once when late for a West End performance. Approaching the theatre, I noticed a crowd of tourists coming towards me. I took out my phone and pretended to talk on it to avoid being stopped. Then my phone rang. I was mortified and will never forgive myself.

I’ve never had ambitions. I’ve always thought whatever happens, happens, go with it. I’m still an actor for hire, but I’m cutting down on long runs. I want to spend more time with my grandchildren.

I turn 80 next year and I can’t remember getting here. I feel young, energetic and positive, and I don’t really want to act my age.

Travels with Agatha Christie & Sir David Suchet is on Channel 4

Photograph by Neale Haynes