Gandalf the Slightly Greyer?

"Gandalf is in Middle-earth to keep an eye on everybody, and that can be a rather serious matter," says Ian McKellen, not all that seriously, on the phone from his London home the other day.

Absent last week from the Wellington, New Zealand, world premiere of "The Hobbit: An Unexpected Journey," McKellen, of course, is Gandalf — the wise old wizard and guiding spirit in "The Lord of the Rings" trilogy, and now in "The Hobbit" prequel trilogy, too.

"The Hobbit: An Unexpected Journey," Peter Jackson's hugely anticipated first installment, shot at 48 frames per second (twice a film's normal speed) and in 3-D, opened Friday.

Set, as J.R.R. Tolkien wrote, in a time "between the Dawn of Færie and the Dominion of Men," "The Hobbit" follows the furry-footed, reluctant hero Bilbo Baggins as he embarks on a mission to claim a huge treasure guarded by an evil dragon, Smaug. He is joined on his quest by 13 dwarves, and here and there — when crises arise — by the mysterious, mischievous Gandalf. "The Hobbit: The Desolation of Smaug" and "The Hobbit: There and Back Again" are to be released in late 2013 and 2014, respectively.

Although it has been a dozen years since McKellen donned the wizard's hat for the "Lord of the Rings" trilogy — and although "The Hobbit" takes place more than a half-century earlier in Middle-earth chronology — the actor, now 73, believes age is not an issue.

"Here's the good news for the fans — or the bad news, rather," he says with a laugh. "I'm exactly the same as I was before. I hope that I don't look 12 years older. It's true, Gandalf is actually meant to be 70 years younger — or is it 60? — but actually he's 7,000 years old, so who's counting? I think we'll be OK. ... I don't know in what sense he could be younger. He's very much the same old soul."

That said, McKellen is happy to be returning as Gandalf the Grey, not Gandalf the White — the back-from-the-dead incarnation seen in the later, darker stages of "The Lord of the Rings" narrative.

"Gandalf the Grey was always the guy I prefer," he notes. "Gandalf the White was driven to do a particular job, whereas Gandalf the Grey is a bit more humane. He likes to party, and smokes and drinks and so on."

Tolkien published "The Hobbit" in 1937. The children's book is much shorter, and jauntier, than the trilogy that followed, and McKellen says that Jackson's prequel reflects that difference.

"The whole atmosphere of the book, the tone of 'The Hobbit,' is of a kid's adventure story, told in the first person by Tolkien who is introducing young people to the notion of Middle-earth. A lot of it is very light-hearted.

"It gets considerably darker in 'Lord of the Rings,' where, of course, it's about saving the world. ...

"However, 'The Hobbit' films are going to lead onto 'The Lord of the Rings.' Peter sees it as a six-part film and so there are dark areas, and a lot of that lands on Gandalf's door, because he's the guy who is keeping an overall watch on the quest of the dwarves to regain their land and their gold from the dragon — and that will affect the actual stability of Middle-earth as a whole.

"And so there's a sense of foreboding, and it's Gandalf who goes and roots that out whilst the dwarfs get on with having fun, really."

For a time in the late-2000s, Guillermo Del Toro was going to direct "The Hobbit." The "Pan's Labyrinth" creator moved to New Zealand and spent several years working on the scripts and production strategies for what was then envisioned as a two-parter. But frustrated by the slow pace, the Mexican filmmaker finally quit the project.

"I was disappointed not to have a chance to work with him," says McKellen, who met with del Toro several times. "And then disappointed that the film apparently wasn't going to be made at all. Then it all changed because Peter decided he would take it on after all."

McKellen says that for all Jackson's success — "The Lord of the Rings" is one of the highest-grossing film series of all time, and Jackson's Down Under studio complex and visual effects companies have transformed the New Zealand economy — the director is still very much the same fellow.

There is one notable change, however.

"He wears shoes — he didn't used to wear shoes. But I wouldn't say he's become more sophisticated. It's just that he wears shoes now. Perhaps his feet were beginning to ache."