TV legend John Simm stunned as he learns his dad is NOT his biological father in explosive documentary

LIFE On Mars actor John Simm discovered his dad was not his real father on a trip into the past for ITV show DNA Journey.

John, 54, got the shock when he appeared on the programme with time travel police series co-star Philip Glenister.

The ITV genealogy show pairs two celebs an episode to make family discoveries using DNA tests.

John, who took part only because Philip, 61, asked him, said: “The DNA results came back and my dad, is not my dad. It turns out he isn’t my biological father, which is a bit of a shock. It spun my world, and everything I thought I knew wasn’t real.”

He used to sing and play guitar with the man he called Dad, Ronald Simm, in Lancashire working men’s clubs — and it turned out his real father often drank in the same places.

He added: “The thing that blows my mind, he might have been in the same pub one night and watched me play.

“It’s one of those mad, Back To The Future, Life On Mars things.”

But John, who has two sisters, Carol and Nicola, also admitted it was an incredibly sensitive discovery because he was so close to Ronald, who died in 2015 aged 78.

He said: “I’m glad my dad isn’t alive to see this because I’m sure he’d be shocked and upset.”

His mum Brenda, 73, was also “absolutely floored” by the news.

He said of her and Ronald: “They were together and then they split up and they were both with other people and then they got back together and had me.”

The show’s research led John to Featherstone in West Yorkshire, to discover his real father Terence Naylor died in 1998.

But he found Terence had a daughter Karen — and meets the half-sister he never knew he had in emotional scenes in the episode a week tomorrow.