The ex-EastEnders and Gavin and Stacey star searches for some long-lost relatives, including his real grandparents, in BBC1’s Who Do You Think You Are?

Your search in Who Do You Think You Are? is focused around finding your 83-year-old mother’s natural parents, because she was adopted, aged two. How important was it for you to track down these blood relatives?
“Growing up in London, I never had any reason to doubt that my wonderful maternal grandparents, Fred and Nel White, weren’t my real grandparents. I only learnt about my mum’s adoption as an adult. I got more curious about my real grandparents, Albert and Catherine, once I started writing my autobiography (Mummy’s Boy).”

Albert and Catherine Day were married in 1927, the year your mum, Jessie, was born. What happened then?
“They split up. Albert was 24 and Catherine was only 17, so the marriage was probably doomed from the start. The last sighting of Catherine was two years after my mum was born. No one really knew what happened to Albert – he disappeared from my mother’s life, and from his family’s lives too.”

Once you’d agreed to do Who Do You Think You Are? were you nervous about what you might find?
“I suppose some people are, I wasn’t. It’s an adventure because the TV researchers give you no clues at all – that’s the whole point. They don’t let you in on anything. You tell them what you know and then they find out whether there’s a story to be told.”

But of course, you were mainly doing this for your mum…
“She’s always figured that one day she would see her mother, so, as far as I was concerned, if there was a possibility that this might open things up for her, it would be wonderful. In finding out about her mum and dad, that would be the answer to a mystery as far as I was concerned.”

Surely finding your mum’s real parents, Albert and Catherine, was going to be a long-shot?
“The last sighting of Catherine was in 1929, two years after my mum was born, when she was actually given up for adoption. And from that point on, there was no trace of either Catherine or Albert. He’d long since disappeared. Information about Albert’s side of the family comes together quite nicely, although at a certain point he disappears again and we don’t know what happened to him.”

Does research into Catherine’s side of the family come to a satisfactory resolution?
“It does really, the only thing is my mother will not be seeing her mother, who died in 1992. But she suddenly finds that she’s got a living relative in Los Angeles, a half-brother. It’s quite a thing to happen in your mid-80s!

Have they met?
“After we’d filmed he programme he came over and saw her. It was just as important for him to find out that he’d got relatives back in England that he knew nothing of. All he knew was that he’d been born in England of a mother and father who emigrated to America and then became naturalised Americans. He’d no inkling at all that his mother had had a previous life.”

How did Jesse react?
“I put her on the phone during the programme. I was sitting in this uncle’s living room in America and I said, ‘Why don’t we speak to my mum right now?’ So I phoned her at home and said I’m sitting in the living room of a person who turns out to be your half-brother. She’s pretty open to surprises, my ma. I guess she was wondering all the way if something would turn up.”

It must be hard for Jesse to accept that she’ll never meet the woman who brought her into this world?
“My mother was living in north London just a few miles away from where her mother was living with Fred and Nel in Camden, and having an entirely different existence. She wonders why Catherine just went away and left her, although that’s partially answered in the programme.”

You seem amazed and a bit shaken to discover Albert comes from a long-line of famous travelling entertainers…
“It made me realise it wasn’t a fluke that I got into this business. To find out that on one side of me there’s generation upon generation of people that travel around entertaining people… it’s not a surprise really. But also there’s that thing of always being on he move – it’s in my mother as well. As soon as my mum gets to a new place to live, she starts looking in the property pages because she’s figuring out where she’s going next. I’m like that as well.”

What was the most emotional moment of the programme for you?
“The very end of the filming and summing up what the whole experience meant to me. I understood far more about myself and that really was emotional. You find out about these young people who met and found out there was a child on the way, and then they got married and both disappeared.”

During the show you also discover you’ve got all these relatives you didn’t previously know about. It’s going to bump up your Christmas card list!
“Evidently I’ve got thousands of cousins all over the world now. I’ve already met a few of them, which was really lovely, and I’ll stay in touch, but I don’t do Christmas cards. No doubt sooner or later I’ll meet a whole bunch of them.”