As he stood on the set of the world’s ­biggest TV show to deliver an ­explosive line, actor Dean S Jagger breathed deep and savoured the moment.

His memories of ­sweeping up at a ­mattress factory for the minimum wage were still fresh.

Dean, 37, had grown up in Yorkshire and dug trenches to pay for acting ­lessons. Now he was in the ­spotlight and living his dream.

He was ­shooting a scene as Smalljon Umber in the smash hit Game of Thrones last autumn.

Dean had to warn him mum Donna that he'd be dropping the c-bomb in Game of Thrones (
Image:
John Gladwin)

Before it was screened, a few weeks ago, he had to warn his mum Donna, 56, and his grandparents that he uses the c-word.

Lord Umber was at Winterfell asking sadistic father-killer Ramsay Bolton, played by Iwan Rheon, for help fighting tribes on his land in the north.

Dean recalled: “As we began ­filming I knew I was about to say my ­infamous line. I walked to my spot, I turned and just thought, ‘Wow, I really am here. My dream has come true.’

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Dean now stars as Smalljon Umber (
Image:
John Gladwin)

“I then turned to Ramsay and bluntly uttered the line: ‘Your father was a c**t and that’s why you killed him.’”

Dean’s scene may be the first of many because GoT is never predictable. All the stars are sworn to secrecy about the plot so it is a breathtaking surprise when a famous face is killed off.

The show is huge. Each episode costs nearly £7million. In the US alone there are more than ten million fans and specially ­edited versions are made for many ­millions more in India and China.

Dean ­auditioned for series six in June 2015.

He told the Sunday People: “I prayed for it. When I heard I got the part my knees buckled. It was a life-changing moment.

Dean whilst labouring for his dad, which he still does on occasion now (
Image:
John Gladwin)

“My dream had come true. I had to keep it secret for months. I can’t even tell my mother if I am going to be in more ­episodes. My agent says Smalljon is ‘an ­impactful role’ and that’s all I can tell you.”

Dean had spent years labouring and digging trenches for his ­builder dad Steve to pay for acting lessons. Sitting in Donna’s home in Wakefield, West Yorks, he is still taking in his rise to stardom – as his mum proudly reels off the ­famous GoT names on his phone.

He said Hollywood bosses “love my Yorkshire accent and my ­stories about digging trenches and work in the mattress factory”.

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Dean and brother Ben, now 36, were professional rollerbladers in the 90s and British champions five years running. At the age of 25 Dean hung up his skates to act.

He said: “Dad would say: ‘When are you going to get a proper job?’ I’d always reply, ‘Never.’” Ben wanted to be a ­director and writer. The pair took a series of manual jobs to make ends meet and saved every penny to fund a short 2009 film, A Night at Robert McAllisters.

Dean said: “We ate porridge for two months and were so broke we once shared a ­sandwich. I didn’t tell Mum. Digging trenches made me so hungry for acting success.

“The lads at the mattress ­factory were great. I went back to see them last week.”

Dean with his dad Steve and brother Ben (
Image:
John Gladwin)

Maintenance manager Dave Brown, 38, said: “Dean was a hard worker. Movies were his passion and I knew he’d do well. I’m proud of him.” After filming Game of Thrones, Dean joined Ben, now a film director, in Los Angeles.

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Dean has just finished filming sci-fi movie Scorched Earth in Vancouver, Canada, starring John Hannah and directed by Sliding Doors’ Peter Howitt.

He has also appeared in Corbin Nash, directed by Ben, with screen legends Malcolm McDowell, Rutger Hauer and Lost Boys star Corey Feldman.

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Donna, who amicably split from Dean’s dad 18 years ago, is confident that fame won’t change her son. She said: “He’s too grounded. All my sons are. If he wasn’t I’d soon tell him.”

Ben agreed, adding with a laugh: “We are so ambitious but only last week we were helping our dad build a house. That keeps us grounded all right.”

So while millions are gripped by GoT, Dean remains at his mum’s for a few more weeks before returning to LA, enjoying her roast dinners and ­seeing his old schoolmates.

And he’ll be working – not learning lines, but labouring for his dad.