Sir Patrick Stewart remembers growing up with an abusive father, Alfred, in a powerful episode of Who Do You Think You Are? He researches his parent’s traumatic World War II experiences in an effort to understand how Alfred became such an angry man. The former Star Trek: The Next Generation actor tells TV Choice more…

The programme focuses on your father, Alfred, and delves into the history of his World War II career. Did you know that would be the case?
No. I gave them [the programme-makers] some background on what I knew about my ancestors, and of course when you do that there’s no guarantee there will be a programme. Sometimes they come back to people and say, ‘We don’t have a story.’

I had become convinced that it would be about one of my two grandfathers, and it proved not to be that at all. And I was into the second day of filming when I finally managed to add up all the clues and realised that it could be someone much closer to me than a grandfather.

At that point, I was hoping that I’d find I’d have a Viking warlord as an ancestor, that kind of thing, but it proved to be something totally different.

You also share painful memories of Alfred being violent towards your mother, Gladys. Was finding out about his past an unexpected and emotional journey?
The way that these programmes are made is that everyone involved knows far more than the subject — ie, me — so day by day, hour by hour, sometimes minute by minute, I didn’t know what was going to happen next.

How did that make you feel?
Fine, once I’d got used to the idea that they probably weren’t going to spring ugly surprises on me. There was one instance when I was looking at some documentary records to do with a magistrate’s court and I got very uncomfortable because — as far as I was aware – no one in my family had had any dealings with the courts. But indeed, there was the evidence.

At one stage, I only worked out from the sign-posts, seen from the vehicle that we were in, that we were travelling to Portsmouth. And if it meant Portsmouth, it probably meant we were going somewhere into Europe. But I didn’t know until we were crossing the channel where we were actually going. It’s that secretive. And then when we were in France, I had no idea where we were going.

Did it feel like a privilege taking part?
That’s an important word. There were numerous occasions when I felt extremely privileged. There were conversations that I had with people that were really quite potent. And to be in locations where a member of my family had stood, during times of real danger, risk and intensity, and to be on that spot knowing that he had been there, was extraordinary.

You’re about to start shooting a movie, Hunting Elephants, in Israel, but you’ve also been to a few sci-fi conventions recently. What are they like?
They’re very enjoyable. There are thousands who attend these events. One of the things I do is appear on stage to talk about the work I’m doing and answer questions from the audience.

Are people star-struck by you at these events?
I suppose so, somewhat. It’s a curious thing about science-fiction and fantasy. You exist for the people who follow the show in an amazing world — a fantastic world — and I think to find that that person is flesh and blood, and a regular individual, comes as a little surprise.

What did your girlfriend, singer Sunny Ozell, think of you taking part in Who Do You Think You Are?
She was one of the people who was most enthusiastic. She has not seen the film yet. She will be seeing the film in about two or three weeks time when she joins me in Israel.

BBC1, Wednesday
David Collins