This period of intense physical discipline has coincided with a time of huge stress and radical upheaval in the actor's emotional life. Last year, he and his wife Alison, 33, who have been married for eight years, separated. They're now in the final delicate stages of divorce - which makes any discussion of what went wrong difficult, to say the least.
In the meantime, Robson has begun a new life with 44-year-old former model, Vanya Seager and though she's widely reported to be expecting the actor's baby in the summer, Robson is yet to make the usual public declarations about the subject.
"Alison and I are getting a divorce," he says. "I think people change. But that's all I'm prepared to say. I don't want to talk about Vanya now. But when the time is right, I will." Subject firmly closed. Were it not for the actor's belief in the power of publicity and his passion for the projects he's involved in he wouldn't be here at all.
After all, he has spent the last few weeks avoiding journalists and photographers who have followed him and Vanya around, reporting their every move. "But I have to promote these shows," he says simply.
That said, we search for safer ground and return to his role in The Last Musketeer, which he says has been a major challenge. "Fencing is far and away the hardest thing I have ever done," he says.
"Even though the guys who trained me, David Rollo and Britain's number one fencer, Dannie Mackenzie, make the whole thing look so effortless. With their help I got up to a reasonable standard. But if you matched me with one of these guys, the most I'd last would be 30 seconds and they'd turn the average swashbuckling Mask of Zorro type into a tea bag.
They'd perforate the guy. You watch them fence and you think, 'God, these guys are artists'. Modern fencing is wonderful, sexy, almost like ballet. I knew I could never get to their level of achievement but I'm chuffed that I was able to do most of the fencing shots myself."
The Last Musketeer was filmed on location in Scotland. It centres on Steve McTear (played by Robson) a fencing champion who becomes involved in underworld crime when his sporting ambitions fail. Eventually, he falls foul of both the police and the underworld, and foes on the run from both ending up at a girls' public school where he takes cover as the fencing coach.
"Mctear's the type of guy who sleeps, eats and breathes fencing. He knows he's the best fencer in the country but because he's working class he hasn't been given the breaks that he's needed. So there's an element of resentment in him. By the end he's gained an understanding."
Now aged 35, Robson is drawn, he says, to roles where there is an obvious arc - a learning curve of experience. "They're roles I probably couldn't have played in my 20's," he admits, "because you need a certain level of maturity and experience to get your head around them."
It's undeniable that elements of the roles that he's now playing seem to have echoes in his own private life. Already, for example, he's talking about another project, Take Me by 'Forgotten' writer Caleb Ranson, in which he plays a man whose marriage is breaking up. And in another, Close & Innocent, he explores his deeply rooted political beliefs.
"It's about what a right wing government did to the working class North East. The collapse of the mines, the unemployment - things I witnessed first hand, things that have shaped my politics and my beliefs, and made me, to some extent, who I am.
But I don't find it hard to reconcile my socialist beliefs with earning good money and I'm not embarrassed by wealth," he says. "If I was embarrassed, then I'd be unhappy.
If he's unhappy about anything right now, it's that, recently, the press has found his private life more fascinating than either his work or his public conscience.
"I'm upset that Alison and her family have been hurt by so much unwanted attention. They're wonderful people, and they really didn't deserve that kind of treatment. It's been upsetting for everyone," he admits, "But I'm trying to be an optimist and to look to the future. I've got plenty to look forward to, after all."
Daphne Lockyer - TV Times