Jeremy Irons is rolling a cigarette and sipping cappuccino on a warm spring afternoon in Pasadena, in the sedate manicured gardens of a five-star hotel. The British actor stands out because he's so recognisable with those hollow cheeks and floppy grey hair - but also because he smokes, a habit that's practically outlawed in California.

He's impeccable in a sharp black suit and white open-necked shirt. There's something quintessentially English about Irons that is still reminiscent of his first big role as Charles Ryder in Brideshead Revisited, the 1980 TV drama. But he's steered clear of aristocratic English gentlemen for most of his career, choosing more unsettling characters. "I prefer a challenge. I like to make life difficult."

He says he's about to spend a "difficult" week working on a screenplay with the director David Lynch. "It's good to have challenges, because I've got a bit lazy in the past 14 years. I've never been passionate about acting, and I find more and more that I work to live the life I want to live. An actor like Al Pacino lives to act. I'm not sure though, there's something about the detachment I have, the feeling of the lack of importance about what I do, that is healthy."

He may lack Pacino's passion, but you'd never know that from his films. In 1998, he played the sadistic twin gynaecologists in Dead Ringers. In Reversal of Fortune (1990) he won an Oscar for his portrayal of Claus Von Bulow, the socialite accused of murdering his wife.

In Kingdom of Heaven, Ridley Scott's new sword-and-sandals Crusader epic, he gives another richly layered performance. Orlando Bloom stars as an idealistic French knight who defends the city of Jerusalem from the Moslems, led by their ruler, Saladin. There are big battles and a romantic storyline, but the film examines religious intolerance.

Irons, 56, plays Tiberias, military adviser to the Christian King Baldwin IV. "I quite like playing dry old badgers like this. He's lost his idealism. He's an old warrior and has fought his battles. But he's broad-minded; he's a closet Moslem, actually, heading toward retirement, and he realises that people are in Jerusalem to make their fortune and their name, not for the glory of God, whatever that be."

Unlike Tiberias, Irons says he's not a cynic. "Am I a spiritual person? I hope so. I'm not very intellectual, I'm instinctive. My family's Catholic," he says, referring to his wife, the actor Sinead Cusack, and their sons Sam, 27, and Max, 19. "I don't go to church much because I don't like belonging to a club, and I don't go to confession or anything like that, I don't believe in it. But I try to be aware of where I fail and I occasionally go to services. I would hate to be a person who didn't have a spiritual side because there's nothing to nourish you in life apart from retail therapy."

Film-making hasn't always been satisfying for Irons, which is why he's choosy about his roles. "I've loved it, and I've loved being successful." He smiles. "But I looked at The French Lieutenant's Woman recently, and I don't like what I do very much. I could have done more with it, and I wish I'd had more experience when I made that film. Anyway, I'm never satisfied. I think were I ever satisfied with my work, I'd be in trouble."

Interestingly, Irons enjoys being famous. "The world turns into your village. And I like being able to go to the off-licence and borrow a tenner because I've no money on me and they know who I am and that I'll pay it back. The downside is that you have to create privacy. So on holidays you just have to spend a bit more and hire a boat instead of lying on a beach.

"I still enjoy acting," he says. "Even if I were a jobbing theatre-actor, I'd think I was lucky. But I'm very easily bored making films. I don't like Hollywood bullshit."

He was recently in Being Julia with Annette Bening and has a small role as Pucci in Disney's new Casanova.

Irons was drawn to Kingdom Of Heaven because he admires the director. "Ridley is very, very good at what he does," he says. "He's at the top of his game. He's brilliant at action - we saw that with Gladiator - but what's great about this movie is that it has a strong emotional, spiritual centre. It's fully fledged."

Liam Neeson and David Thewlis also appear in the film, which was shot in Morocco and Spain. "It's a fascinating period to research," Irons says, "because the kingdom of Jerusalem was rather like Hong Kong before 1997. There were lots of expats living a pretty good life out there in Jerusalem. It was a great place to be, compared with the Dark Ages of Northern Europe."

He pauses and picks up a San Pellegrino bottle holding a huge pink rose, and holds it under my nose. "Just smell this, it's amazing," he marvels. "You rarely find a rose with such a strong scent."

The distraction seems indicative of his approach to acting. He enjoys it, but there are other things he enjoys more. "Basically, I want to keep working, so I don't worry about the size of the character - if it's interesting, I'll do it. It's quite nice doing smaller roles, in some ways. It means I get home more, and I can get on with my life."

You'd think there would be plenty of big-role opportunities for an actor of his ability, but it seems not. "The movie industry is run by accountants in Hollywood and it's as simple as this; everyone has a number on their computer." He smiles, then shrugs. "They can look up Jeremy Irons and see what my last five movies have made. Say you want to make a $20 million picture, which is relatively cheap - if Jeremy makes $9 million, the director makes $5 million, then you need a leading lady, and they just go through those figures - that's how casting happens. And none of my movies has made a lot of money."

His last leading role was in Adrian Lyne's adaptation of Lolita in 1997. "The film was a big disappointment," he says, "and because of the subject matter it didn't get a theatrical release here, so my stock is quite low in America. All it needs is for me to do a picture that's successful at the box office and I'll get offers. I am respected, though," he says. "They'll say, 'We want a bit of cred, let's get Jeremy Irons on board'."

Recently, Irons has found a different kind of pleasure restoring his 15th-century castle in County Cork, Ireland. He's more animated talking about his six-year building project than his films. "Doing the castle was sort of terrifying, rather like making a film. I got a crew together. When we were going flat out I had 40 people there.

He pulls photos from a battered leather satchel and shows me a dozen angles of his imposing home. "It's not that big. It sleeps about 12 if they don't mind sleeping double. It's a wonderful sanctuary, incredibly quiet because the walls are so thick." He points to one picture: "On the top of that tower there's a Jacuzzi. Although the castle's a very male shape, with two towers, inside it's like a womb. It's very special and romantic."

Are he and Sinead still romantic after 27 years? "I don't know. I don't like talking about my marriage," he says, a little uneasily. "You know, my wife's an amazing woman, a very forgiving woman, which you have to be with me." Why forgiving? "Because she holds the fort. I went off filming while she raised our children. She put her career on hold for a long time.

Their son Sam is a photographer, and Max is auditioning for drama school. "I encourage my children to do what they want. I was so lucky that I settled in a business that suited me without giving it a lot of thought," Irons says.

He owns five houses around Britain and Ireland. "Home is wherever we are together as a family. But I love the castle. It somehow opens up your sensitivities, as well as being very calming. I think my soul is probably lingering around the castle."

- Independent