Thomas Cromwell, brilliant and dangerous, coiled to strike, was Henry VIII's right-hand man, the lawyer who would persuade the pope to annul the king's marriage so he could remarry (and remarry and remarry) and beget an heir.

Ben Miles, open and cheery, is the actor who plays Cromwell in the Royal Shakespeare Company's Wolf Hall, Parts One and Two, a two-play package based on Hilary Mantel's award-winning novels. Now in previews, it opens April 9 at Broadway's Winter Garden Theatre in what may be the most-anticipated New York show of a heady season.

Wolf Hall, Part One begins with Cromwell's being summoned from Yorkshire to Cardinal Wolsey's palace. Wolsey's secretary says accusingly: "Cromwell. Late." Cromwell replies, "Yes - isn't it?" That deflection reveals his genius, his restraint, the self-mastery of a thug-turned-courtier who rose to power in the treacherous court of Henry VIII.

Mantel's Wolf Hall and Bring Up the Bodies have been adapted for the stage by Mike Poulton for the Royal Shakespeare Company, with Jeremy Herrin directing and Nathaniel Parker (BBC's Inspector Linley) as Henry. They've also been turned into a six-part BBC television series by Peter Straughan, under Peter Kosminsky's direction, that starts next Sunday on PBS.

Ben Miles is Cromwell on stage; Tony-winner Mark Rylance is Cromwell on screen, with Damien Lewis (Showtime's Homeland) as Henry. An embarrassment of very different riches.

Mantel, deeply involved in both adaptations, has followed the production to New York and meets frequently with Miles. What do they talk about? Miles explains:

"One of the great thrills for me in this whole project has been getting to know and collaborating with one of our greatest novelists. I had been thinking about the opening scene and wondered what would have been going through Cromwell's head on his ride down from Yorkshire, so I e-mailed her. Back came four pages, it was like a chapter from the book: his son, what was going on in Europe, what was going on with his property, how he felt about Martin Luther, what was going on with Wolsey, the weather, the number of horses he'd have to use on the journey - everything - and I was just astounded by this.

"I thought, 'Wow, there's this whole seam of information,' so once we were in performance, I'd send her moments that struck me, and she would respond with her insights into scenes, having watched the play hundreds of times. . . . What she doesn't know about 16th-century England isn't worth knowing. She's willing to give any information she has. The shop's open all the time."

So, given this lengthy total immersion in the character, does Thomas Cromwell bleed into Ben Miles?

"I'll find myself thinking in a situation, how would Cromwell react to this? Often, when we're reworking a scene or modifying words or phrases, things will come out that seem to come from somewhere else. You spend so long absorbing a character and a manner, your unconscious somehow starts to act."

Interviewed in his Winter Garden dressing room, Miles, 48, is wearing contemporary black: jeans, T-shirt, and a denim jacket. Cromwell's fur-trimmed robe hangs nearby. With intense brown eyes, a cadaverous face, and slept-in hair, he can create the Cromwell who, in Poulton's words, "looks as if he might stab you under a bridge on a dark night."

One of the plays' most electrifying moments comes in Part Two, when an exasperated Cromwell almost punches Henry and then, horrified, drops to his knees, having revealed in a flash the streetfighter beneath the suave lawyer. What led to that?

"That just happened one day," says Miles. "As a kid, Cromwell had been subjected to great brutality, and was capable of great brutality, so to have that instinctual reaction seemed to come naturally. Those moments are interesting - where his baser nature exposes itself. The only thing to do is fall to your knees and just hope you don't wind up in the Tower that afternoon."

Asked whether playing before an American audience is different, Miles says, "They let you know how they're feeling. That's great - it ups your game. The audiences in Stratford" - Stratford-upon-Avon, the Royal Shakespeare Company's home - "were very different than in London, where audiences are more diverse: tourists, the London intelligentsia, and a wealthy set of people, lords and ladies, descendants of the characters in the show."

He's a fan of the BBC Wolf Hall series, especially of Rylance, his TV counterpart as Cromwell and well-known to American audiences from his Tony-winning Broadway appearances in Boeing-Boeing and Jerusalem.

"Mark's a fabulous actor, and I know him as a colleague and a friend - I love him dearly, and he's been a great inspiration to me, a great help in my career. My first job was understudying him, so I was delighted when I heard he was playing Cromwell.

"To watch it was a real privilege. I have such a peculiar viewpoint, since I've never see the show I'm in, and to watch Cromwell was fascinating. It's helped me a lot to think about him objectively. . . . Cromwell was a great lover of life, great largesse, gave great parties, kept a leopard, for God's sake - he wasn't a shrinking violet, but he wasn't an egomaniac, he wasn't a showman. He was a man who did things."

The television production provides an interesting contrast to the stage version: Onstage, everything is fast - the talking, the walking - while on-screen, everything is slow, with whispered conversations and long shots down empty corridors. Two very different Cromwells, two very different adaptations, two very different media.

In the second novel, Bring Up the Bodies, there is a superb, tiny scene in which Cromwell and his grown son stand side by side, gazing at a (now famous, then new) portrait by Hans Holbein that has just been sent to the house.

"I look like a murderer," Cromwell says. His son replies, "I thought you knew."

The portrait now hangs in the Frick Collection, at 70th and Broadway, where you, too, can gaze at it. Ben Miles has.

Toby Zinman reviews theater for The Inquirer.