Actor John Simm's life is turned upside down as he uncovers earth-shattering 54 year family secret

Life On Mars star John Simm, 54, signed up for TV show DNA Journey With Ancestry as a favour for pal and fellow actor, Phil Glenister, so they could research their family trees together

Acclaimed actor John Simm's family life has been turned upside down by a new ITV series, which leaves him saying "everything I thought I knew wasn’t real".

Life On Mars and Doctor Who star Simm, 54, signed up for TV show DNA Journey With Ancestry as a favour for pal and fellow actor Phil Glenister so they could research their family trees together.

But Simm got the shock of his life when he was told his dad was not his biological father. He said: "So cut a long story short, the DNA results came back, and my dad, he's not my dad."

The programme begins with John recalling an email followed by a conversation he had with his mum Brenda before he took his DNA test as filming began last year. His dad Ronald Simm died in 2015.

He said: “When they had me, in the sixties, they were both young…they were together and then they split up and were both with other people and then they got back together and then they had me. And I’d never heard this story before.”

John explains that his parents spoke to a doctor, he adds: “And the doctor said: ‘It’s absolutely fine, the dates are fine.’ But it turns out he isn’t my biological father. Which is a bit of a shock.”

John, who was brought up with two sisters, says that he considered pulling out of the film but then decided to utilise the experts to find out about his biological father called Terence. He says he is glad his dad Ron is not around to learn the news which has "floored" his mum.

The film then sees John and Phil head to Featherstone in Yorkshire where they meet a historian, who reveals that John’s biological father sadly passed away in 1998.

John is given details about his biological father’s upbringing and then discovers that he used to live in the same area and drink at the same working men’s clubs that John and his dad used to play gigs at when John was a teenager.

John says: “The thing that blows my mind, me and my dad, we played around here loads of times, we definitely played here a lot and he might have been in the same pub one night and watched me play.”

John and Phil go on to meet a club steward who has lived in the area for many years and tells John that his biological father lived above a working men’s club with his parents.

John says: “I can’t get it out of my head, because we played this area in the 80s and he was here and he was in working men’s clubs. It’s one of those mad, Back To The Future, Life On Mars things.”

There are moving scenes as John then sees photos of his biological father and learns more about him, including that he married and had a daughter, John’s half-sister Karen he never knew he had.

After getting his head around all the new information, John then meets his half-sister who says Terence - known as Tel - loved getting up on stage and singing too.

John says the revelations explain why he always "felt a bit different" when he was younger growing up with his sisters Carol and Nicola. And he still is shocked by the idea his biological father very probably saw him playing a gig at some stage.

Speaking to Karen, he said: "If he happened to be in on a Friday or a Saturday night in one of those clubs, he would have seen me play. Wow, that's mad, isn't it? Yeah, that's really bizarre. Mind blowing."

Asked how the revelations have made him feel, he added: "I mean, I was really close to my dad. He was like my best mate. But having said that, there was always something, I don't know what it was, I really felt different. And I always felt a bit guilty about it. But a lot of things sort of fall in this place. I kind of feel not guilty about feeling different."

John married his wife Kate Magowan in 2004. They have two children, a son Ryan and a daughter, Mollie.

• DNA Journey with Ancestry returns to ITV1 and ITVX on October 9 with episode one featuring John Simm and Philip Glenister

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