Slender he may be, but Lewis recognises his broader qualifications for the role. "I think there's no question," he told the Radio Times, "that it helps having had the kind of schooling that I've had, to play a king. Just the way, the sort of court structures, the hierarchies, the way they're set up. It's something I feel I implicitly understand."
Born into a wealthy family of illustrious lineage, Lewis, as one interviewer wrote, "has the kind of class credentials that make Hugh Grant look like a reform school oik." To pretend otherwise would be, well ... acting.
Yet beyond his early TV breakthrough as Soames Forsyte in The Forsyte Saga, Lewis has been noticeably sparing in his embrace of "toff" roles. He has dulled his diction and widened his range, but not entirely avoided the perils.
Last year he annoyed Sir Ian McKellen by saying that he didn't want to end up as "one of those slightly over-the-top, fruity actors" who finish their careers "playing wizards".
McKellen curtly replied: "No one needs to feel sorry for me, or anyone else who has fallen victim to success."
The challenge in playing Wolf Hall's Henry is to make the character both familiar and different. The king, at least before the psycho-drama of Anne Boleyn's destruction, comes across as a far smarter, more optimistic and resolute figure than the semi-comic monarch of popular culture. Cromwell, too - his deadly, mostly mysterious consigliere - emerges as a complex if biddable brain around which the whole Tudor enterprise revolves.
"Now is the time for you to become king," Cromwell informs his master.
"I keep you because you are a serpent," is Henry's reply. "Everything that you are, everything that you have, will come from me."
This was never going to be an ordinary role. Mantel's Man Booker Prize-winning books have become a global phenomenon, and her readers tend to have a strong sense of what the key characters should be like. Lewis claims to have read his history, and if he hadn't, the hands-on Mantel would have filled him in.
"I think we all have this understanding that he was this womanising, syphilitic, bloated, genocidal Elvis character," says Lewis. "I see in Henry nothing psychotic. I don't see a psychopath. But I think I do see a sociopath, someone who is capable of great love, great affection and I think he craved that."
For all the enviable possibilities that lay at his feet, there seems to have been no doubt that Lewis would become an actor, since the days of performing in his bedroom mirror at the age of 10. He was born in St John's Wood, north London, the son of a successful insurance broker. His maternal grandfather had been Lord Mayor of London, and further down the ancestral line was Viscount Dawson of Penn, an eminent physician who euthanised King George V with an injection of morphine and cocaine.
After prep school and Eton, Lewis enrolled at the Guildhall School of Music and Drama, and for years worked as a stage actor, including a stint at the Royal Shakespeare Company. It was hard graft for little recognition and, as he remembers it, no one took much notice of his background. "With the Labour government coming in, even though Blair had been privately educated," he has said, "it felt as though the Old Etonian thing had been put out to pasture."
One night he was playing in a production of Hamlet, when Steven Spielberg joined the audience. The upshot was a part in the director's acclaimed World War II miniseries Band of Brothers.
American audiences quickly took to him, as he quickly took to film work, and some of his best work has been in Homeland, the award-laden political/spy thriller that has run for four seasons, Lewis' character Brody having been killed off at the end of the third.
He is married to the actress Helen McCrory, with whom he has a son and a daughter. He hints that at heart he is happiest back in Britain, doing British stuff. It doesn't get any more home-grown than Henry.
Who: Damian Lewis, former star of Homeland and Band of Brothers
What: Playing Henry VIII in Wolf Hall
Where: On Lightbox from today
