BERKELEY — Their Stradivarius voices precede them. Climbing the stairs for an interview following an afternoon rehearsal of their Broadway-bound production of Harold Pinter's "No Man's Land" at Berkeley Repertory Theatre, Ian McKellen and Patrick Stewart announce their approach through the mellifluous flow of their conversation.

This is small talk you could bathe in, as clear and inviting as a fresh water pond on a lovely English summer afternoon. Consonants are caressed; vowels ripple joyfully through the air. These knighted gentlemen don't need passports — a simple "good afternoon," uttered in their instantly recognizable cadences, should clear them both through customs.

The room seemed distressingly ordinary for a joint interview with two legends of the British stage. But once Sir Ian and Sir Patrick settled into their chairs, the generic confines of this Berkeley Rep office seemed perfectly natural.

These veterans are accustomed to the no-nonsense practicalities of the professional theater. The worldwide fame granted to them by Hollywood franchises — "Star Trek: The Next Generation" for Stewart, "The Lord of the Rings" for McKellen, "X-Men" for them both — has been what McKellen calls "jam."

PHOTOS: Arts and culture in pictures by The Times

Stewart recalled that in the early days of his "Star Trek" series, when he was in denial about his newfound television success and living above a garage in Hancock Park, he started creating one-person shows to perform on weekends on college campuses in California, so terrified was he of losing his confidence in performing before a live audience.

The stage will always be their natural habitat. Why else would these set-for-life septuagenarians opt to star in a defiantly enigmatic Pinter play — a work they will perform in repertory on Broadway this fall with Samuel Beckett's "Waiting for Godot," both staged by British director Sean Mathias.

Of course their role models are those British acting titans of the past who donned theatrical makeup well into majestic old age. Two in particular spring to mind — Sir Ralph Richardson and Sir John Gielgud, both of whom starred in the original London production of "No Man's Land" in 1975 that subsequently came to Broadway.

Richardson originated the role of Hirst, the wealthy alcoholic poet that Stewart is now portraying. Gielgud originated the role of Spooner, the shabby alcoholic poetaster that McKellen is now impersonating. As precedents go, Richardson and Gielgud are the gold standard, but fortunately British stage actors of a classical bent don't see tradition as a zero-sum game.

"Gielgud's Spooner, more than almost any other performance I've seen, was indelible in here," McKellen said, tapping his forehead. "I can do the whole performance as he had done it, and that's how I started rehearsing it. I thought, 'I shouldn't be doing this. Gielgud has done it.'"

PHOTOS: Hollywood stars on stage

Stewart can still hear the gasps when Richardson's Hirst fell to the floor. "There was about [Gielgud and Richardson], which I don't think there is about the two of us, this sense that they were national treasures. And to see one of our national treasures crash to the floor in a play in which they had to say [expletive] and [expletive] was shocking," he said.

The respect McKellen and Stewart feel hasn't stymied them, however. "My impression of their performance was that they were a brilliant facade," McKellen said upon further reflection. "Everything was there. You could admire it, you could be overwhelmed by it. But what you were seeing was the surface, and I think the play merits another approach."

McKellen and Stewart, who worked together in the 1977 premiere of Tom Stoppard's "Every Good Boy Deserves Favour," earned plaudits when they met again onstage in "Waiting for Godot" in 2009 at London's Theatre Royal Haymarket. McKellen was eager to bring the production to New York, but Stewart had his heart set on "No Man's Land."

"I had for 38 years loved this play and imagined one day I would do it but didn't know where or how or under what circumstances," Stewart said. "As Ian and I got to know one another very well during the period of 'Godot,' I felt as though the role of Spooner could have been created for him."

According to McKellen, Mathias brokered a deal between the gentlemen by suggesting to Stewart that McKellen might agree to do "No Man's Land" if Stewart would consent to another go of "Godot." Thus the somewhat unusual repertory arrangement for Broadway, one that threatens to become a trend this fall with Mark Rylance heading the all-male Shakespeare's Globe productions of "Twelfth Night" and "Richard III."

McKellen's doubts about "No Man's Land" stem in part from the way the play, as he succinctly put it, "raises more questions about plot than an audience feels qualified to answer." The dramatic situation of "No Man's Land" is indeed mysterious in that poetically suspenseful manner that has come to be known as "Pinteresque."

Hirst, having met Spooner in a pub earlier in the evening, has invited him back to his stately Hampstead home. It's not clear whether these older gentlemen have known each other before, what the nature of their present business is beyond the frenetic consumption of liquor or why the two male employees who live with Hirst (played by Billy Crudup and Shuler Hensley) feel the need to subtly menace this visitor, who is desperate to be taken on board as a secretary.

The characters bluff and baffle while dispensing non sequiturs. Critics and scholars have sought valiantly to decode the play's meaning. Is Pinter presenting a split image of the artist's identity, one entombed in triumph, the other begging for alms, or could the power games have a more sinister, not to say sexual, implication?

Luckily, actors and audiences needn't crack the mystery to enjoy the work: The greatness of "No Man's Land" lies in its theatrical effectiveness — how well it plays. And McKellen and Stewart, whose Berkeley run ends Aug. 31, perform it like masters, their contrasting manners colorfully accentuating the differences of their characters.