Ewan McGregor is at home in Los Angeles, trying to persuade me that he hasn’t “gone Hollywood”. That making a string of films back to back with Tom Hanks, Jim Carrey, Hilary Swank and George Clooney is all in a day’s work. That leaving the UK behind and moving his family to California is just the latest logical step in his life. He’s a charismatic and charming chap, and he almost has me convinced. And then a duck walks into the room. A duck wearing a nappy.

“Oh, hang on,” McGregor says, looking round. “My duck is making a noise.”

I can tell. This isn’t the quietest or, I’d guess at a glance, most house-trained of guests. So how did a down-to-earth actor, who claims not to get caught up in the fact he makes movies costing millions of dollars, acquire a duck for a pet?

“Well, it’s a long story,” he says grudgingly. No, he’s not getting off that easily.

“OK, it’s just a duck. The kids had a project at school where they hatched duck eggs, and we took one, and now we’ve got a duck. She’s a house duck. She wears a diaper, a big nappy. You can get these nappies from a website that does things for ducks. Otherwise they’d just poo everywhere because they don’t have control of their, ehm, selves.”

At least he has the good grace to laugh at the ridiculousness of what he’s saying. But then again, McGregor has always taken whatever the movie world has thrown at him, good or bad, in his stride.

The last time we met, just over a year and a half ago, he was in an infectiously ­positive frame of mind. We had got together for lunch at his favourite gastropub, just round the corner from his old gaff in St John’s Wood ­in London.

He was coming to the end of a stage run playing Iago in Shakespeare’s Othello, and had received good reviews. Cassandra’s Dream, the film he made with Woody Allen, was just about to open the Glasgow Film Festival, and he was still buzzed about having worked with the legend. He was also ­enthusiastic about Deception, the thriller in which he starred opposite Hugh Jackman, and Incendiary, a terrorism-themed drama starring Michelle Williams.

Now here we are, some months later. Cassandra’s Dream, Deception and Incendiary all bombed at the box office. The gastropub grub has been swapped for Californian cuisine. But don’t think for one minute that McGregor has regrets about making any of those movies or about uprooting his family and settling down Stateside.

“An awful lot of my films haven’t been huge box office successes,” he admits, “but I don’t look at it as being a mark of whether they’re good or not. The film with Hugh, they were still rewriting the ending as we were shooting it and no-one ever quite cracked it. The Woody Allen film I’ll always think is great. I’ll never forget reading the script and being so excited by the story of it. Incendiary … I don’t want to be mean about anyone, but the script involved lots of flashing back and forward. And in the edit, they decided to completely change the structure of the film and make it entirely linear. And it didn’t work very well. I don’t know if people got nervous about the subject. It was a better script than a film.”

California dreaming

Anyone who has followed McGregor’s career – from the early splash of Shallow Grave and Trainspotting to the international blockbusters of Moulin Rouge and the second Star Wars trilogy – might think that the lack of a recent hit and the move to Los Angeles aren’t unconnected. But again the actor sets me right.

“More than anything, I just felt like a change. There’s an element of it that’s about my work, but it’s not the most important element because I was offered scripts that were shooting over here when I was living in London anyway. I bought a house here when I was making The Island [directed by Michael Bay] in 2005, and I loved it. I just felt like trying to see what it was like to live somewhere else. And as a result it has freed me up to think this isn’t it forever. I like it at the moment, but I could go and live somewhere else. It could be anywhere.”

In fact, he tells me, the only difficult thing about the whole process was sorting through the logistics of new schools for his daughters – 13-year-old Clara, seven-year-old Esther, and Jamiyan, the Mongolian girl he and wife Eve adopted, who is also seven.

“The actual decision to move was quite easy,” he insists. “I think the kids were into it, because we’d spent time out here every year anyway, either to do a movie or some work-related thing. And once we had the house, we’d come out and spend summers here, so it was a world that the girls knew and liked. And we’re over on the west side, not far from the sea. We’re not, like, in Hollywood as such. We’re more in Santa Monica, which is a slightly different, more relaxed vibe.”

The new location is a gift for a self-confessed motorbike nut like McGregor, who made two documented trips across the world (Long Way Round) and through Africa (Long Way Down) with best friend Charley Boorman.

“On more days than not, I can get on my bike and tear off without putting on any waterproofs,” he laughs. “That makes me quite happy. I had to pick up some scenes for The Men Who Stare At Goats [his upcoming film with George Clooney] down in the south-eastern tip of California, near Arizona and Mexico, and I just rode down on my bike. It took me the best part of a day, but it was too nice an opportunity not to.”

The Men Who Stare At Goats is the first in a number of films McGregor has coming out that promise to put him back on the A-list. One could be forgiven for thinking that, despite the actor’s excitement over Woody Allen et al at our last meeting, this time he’s really got something to crow about.

Between early 2008 and now, of course, he has appeared as a Vatican priest in a bona fide smash Angels & Demons, the movie version of Dan Brown’s Da Vinci Code prequel. In two weeks time, he stars opposite double Oscar-winner Hilary Swank in Amelia, a biopic of 1930s aviation heroine Amelia Earhart. He also has the comedy-drama I Love You Phillip Morris, in which he plays Jim Carrey’s gay lover, awaiting release. On top of that, he’s currently in Glasgow filming The Last Word with his Young Adam director David Mackenzie, while Roman Polanski is finishing the post-production of The Ghost, with McGregor as a prime minister’s ghostwriter, from the inside of a Swiss prison. “He’s one of the very few completely brilliant directors that I’ve worked with,” is the only comment McGregor will make on Polanski, who could serve up to two years in prison for having sex in 1977 with a 13-year-old girl. Last week, the US formally asked the Swiss authorities to hand over the 76-year-old filmmaker who has been in custody since his arrest September as he arrived in Zurich to attend a film festival.

A cast to die for

But it’s The Men Who Stare At Goats that truly has a cast to die for. George Clooney … Kevin Spacey … Jeff Bridges … Ewan McGregor … It has a nice ring to it, no? Based on Jon Ronson’s non-fiction book of the same name, the film casts McGregor as a journalist who meets a US Special Forces operator (Clooney) who claims to be part of an experimental military unit consisting of “warrior monks” who are attempting to redefine modern warfare by unleashing their psychic powers. You know, stuff like reading the enemy’s thoughts, walking through solid walls, killing a goat just by staring at it.

McGregor seems to have had a blast making the film, and was particularly impressed with the sincerity of his co-star Clooney, a man who puts his celebrity status to good use. “He’s very passionate about his work in Darfur,” says the Scot about his friend’s role as the UN’s peace envoy to the region of Sudan which has suffered a humanitarian crisis due to a vicious ethnic civil war.

McGregor, who passed through the African country on his second motorbike trip with Boorman, said: “It’s so much more than just lip service. He spends a lot of time trying to get very high-powered people involved, getting helicopters down there to help, getting aid into the country. So he really is totally involved in it and, at the same time, very low-key about it; he doesn’t ram it down your throat. I’ve got so much respect for him. And he’s also a very funny man to be around.”

We know Clooney is at the top of his game. But what is it about McGregor as an actor that makes him the right casting for a big American film, albeit one made through Clooney’s production company rather than a major Hollywood studio? I put the question to Grant Heslov, director of The Men Who Stare At Goats and Clooney’s production partner.

“What I like about Ewan is that he feels a bit like an everyman to me,” explains Heslov, who was Oscar-nominated for his script for Good Night And Good Luck. “He’s like the guy you could meet in the pub and just strike up a conversation with. His normal personality is so attractive; he’s handsome in a way that works for the character; and he’s an incredibly funny guy with a great sense of humour.”

McGregor claims he can’t assess his standing within the Hollywood hierarchy, but perhaps his Goats director can. “As an actor, he’s incredibly well respected,” maintains Heslov. “He has an incredible reputation for being a great guy to work with, and that was certainly borne out when I was working with him – professional and pleasure.” So does McGregor still put bums on seats? “I think he does, yeah.”

McGregor, meanwhile, is still trying to convince me that winning Hollywood’s approval has nothing to do with the career choices he makes. Take Amelia, for example. He’d been trying for years to find a project he could share with Swank and it was her, and her alone, who made him want to sign up to the biopic of flying ace Earhart. In it he plays Gene Vidal (the father of author Gore Vidal), a key player in the early days of the commercial aviation industry.

Airplanes played a major role in making Amelia, and not just as props on the set. Because of scheduling conflicts, McGregor ended up shooting Amelia with Swank in Toronto at the same time as he was ­shooting I Love You Phillip Morris with Carrey ­in Louisiana.

“We worked it out by hook or by crook, and literally for two months I went back and forward from Louisiana to Toronto,” McGregor remembers. “If I had a day off, I was on an airplane; and if I wasn’t, I was shooting one film or the other. I found it really exciting, the process of working on two films at once.

“In the middle of these two films there was an Easter break, and Eve and the girls came to Toronto. They met me there, where I was working for a few days, and then we all flew down to Louisiana together and spent a week down there. I mean, I was working but I still had them around for a couple of weeks in the middle of that and, funnily enough, in both locations. It was quite cool for them: we went to Niagara Falls and stuff, and had a bit of family time, which was good.”

So, still not “gone Hollywood” then? Shooting here, there and everywhere? “Last year was Louisiana, Toronto, Puerto Rico, Italy and LA,” he says, reeling off the list. “And since then there’s been Berlin, London and Glasgow. I shot six weeks in LA last year – but Eve and the kids weren’t here because they were in France. You know, it doesn’t really matter where you live as an actor; you’ll probably end up shooting somewhere else.”

Which only begs the question: who changes the duck’s diapers if daddy’s away at work so much?