The pressure of fame has wrecked many marriages in the public eye but Ewan McGregor is determined it is not going to happen to him. In the relatively short time since Star Wars fast-forwarded his international career McGregor has learned a few hard truths about adjusting to being famous. Lounging around in the Hotel du Cap, a Riviera hotel de luxe along the coast from the mayhem of the Cannes film Festival. McGregor adopts an air of cheerful mateyness. But the suspicion lurks that it's yet another performance in an expanding portfolio of roles which has elevated the star at the expense of the person. The McGregor of Shallow Grave, Trainspotting, Nora, Rogue Trader, Velvet Goldmine, The Pillow Book and Star Wars is not the same as the thoroughly romantic McGregor of Moulin Rouge, the flamboyant musical from Baz Luhrmann in which he partners Nicole Kidman. The McGregor who talks to the media now is deft hand at dealing with inane inquiries from journos promulgating agendas (Question: "Do you want to comment on the break-up of Tom and Nicole?" Reply: "No").

Observing him in action at Cannes, he seems a long way from the young actor who once talked happily and endlessly to any journalist who happened to call him.

"When I was less experienced I would feel obliged to answer those probing questions," he told me once. "You would find yourself giving away parts of your life that are nobody's buisness but your own. Then somebody writes about it, and they give it away to thousands of other people, and it's not your own anymore."

He begins to sound like an old Aborigine who believes that being photographed takes away part of your soul.

"Usually the process leaves you feeling empty and depressed because it's not natural to sit and talk about yourself for that length of time. What happens is that emotional memories suddenly becomes just a story rather than the experience itself, as you use the same words and phrases to describe it. I used to go home and feel awful but I'm learning that if I have a responsibility, it's to myself, my private life, and my family."

One of the ways he manages to keep a sense of nomality is to take with him his wife Eve-a French production designer whom he met on an episode of TV's Kavanagh QC- and daughter, Clara, now five. In Cannes, though, there was little time for family fun-he was merely touching down for a couple of days before returning to Morocco where he's filming with Ridley Scott on Black Hawk Down, about the skirmish between US troops and Somalian guerrillas in 1993. His parents-Carol and Jim- had come to Cannes from Crieff, following proudly in his wake up the red-carpeted steps of the Palais for the world premiere of the film.

"They had a great time, and for me it's payback time for all the effort they put into seeing me through drama school," he says.

The McGregor family values appear to be close-knit and caring, despite his reputation as a jack the lad. He admits that his sex scene in Trainspotting caused his wife angst and says he would be equally unhappy were the roles reversed. "It can cause emotional damage to watch your loved one being intimate with somebody else, even if it is part of the job," he says.

That's not the only concern. When he bared all or his art in Peter Greenaway's The Pillow Book he gave on publication the perfect excuse to title a profile of him with the excrutiating line " I do have a very large penis." As a family they grin and bear such indignities. And yes, it helped to have them around in Australia for the filming of Moulin Rouge, followed by work in the same studios on the new Star Wars film (due for release next May)> The lifestyle Down Under suited them all, making it relatively pain-free way to carve out a family life in a rented house in Sydney. McGregor even felt relaxed enough to take part in the gay mardi gras parade. When the pace became too intense McGregor, who turned 30 this year, hived off into the outback on his own.

"I got myself a Harley Davidson and took off into the countryside, which is what I usually do at home. Normally I ride sports bikes. I have never had a Harley before, but out there it seemed to be the thing to have. I bought myself a tent and would go off into the countryside for a few days at a time. There were a lot of people on the Moulin Rouge set, and sometimes it was the only way to preserve your sanity. It was quite nice to be out there in the middle of all that space on your own." The main consolation was that Eve and Clara were there to greet him when he returned. "I have always made sure they come with me. There are too many wrecked marriages in this buisness for mine tobe one. I am in a position to insist that they come, and if anyhone doesn't like that then I won't make the film. It's important: I don't want to miss my daughter growing up because of a film.As it is I'm usually away to work before she's up,and back after she's gone to bed. But at least she knows I am around."

The only blot on domestic harmony occured when he had to spend time in Chicago on an episode of ER, a sure sign of having arrived (he was nominated for an Emmy for his performance as an armed robber caught in a siege). Because he was away for a relatively short time, he broke his usual rule and left the family at home. During his abscence, Clara contracted meningitis and he came back to find her in the hospital.

"Afterwards she was a bit weird with me- and on reflection I would rather not have gone." McGregor seesno dichotomy between his family and his film life. "I don't go to work, and then turn into someone else when I return home. I am the same person, " he insists. "Maybe the sex roles are more confusing now than they have ever been, except that people have always thought they were in a time of great change. That is the nature of human beings. Men now are supposed to be able to be soft and cry, yet still be tough. "So basically we men just flummox about being beaten by women all over the place. The Scots are quite and emotional race. My mother will cry at the drop of a hat-usually with joy ,though. I cry easily, too, and so does my dad, but in America men feel the need to be more macho. That's partly why British actors seem more interesting to them." When McGregor reads about himself he finds his capacity to swear is the factor which shocks him most. The F-word crops up rather frequently. "All the swearing bits come as a bit of a shocker." He liked the fact that for Moulin Rouge he was able to indulge his musical talents. "I'm going to continue recording music because I like it. I'm not signing with a record label or anything like that. I've sung since I was a boy. I did a lot of singing when I was at school in the choir, and in drama school. It is as effective a way to express yourself as acting.

Making films is a long, laborious process to tell a story, whereas singing is a very quick way. You can listen back immediately and change bits. Maybe one day I might do something more, but now I just enjoy it." Asked to name his preferred film from his canon, his natural inclination is to plump for Moulin Rouge, and not just because it is always politic to refer to your latestest project .

"I have never invested more of myself and my passion into anything else. And I have never felt the same way about a director than with Baz on this. He is overwhelmingly dedicated to what he is doing, and he demands no less of you. He pushed me into places I had never even been before. You cannot help but be inspired. He fills you with a confidence that I haven't felt since working with Danny Boyle [Who directed Shallow Grave and Trainspotting]. "He has a special affection for Trainspotting, Brassed Off, The Pillow Book, and his stint on the London stage in Little Malcom, directed by his uncle, actor Denis Lawson who was big influence in easing him into the business in the first place. He wants to return to the theatre next year, through Natural Nylon, the company he formed with Jude Law, Sean Pertwee, Johnny Lee Miller and Sadie Frost. McGregor appreciated the way that Luhrmann took such trouble to create the right climate for him and Kidman to cultivate a chemistry. "The first day we just sat around Baz's house in Sydney talking and talking, having lunch, and then singing around a piano. It is quite exposing doing that when there are just the two of you in a room with the director. So we decided then and there to allow each other to be as crazy as we wanted to be, and there was a lot of giggling and laughing. By the time we started filming and we burst into song it hardly registered that that was what we were doing."

Despite his experience McGregor still suffers insecurities underneath the blase exterior. "There are times when you don't feel very good about it, and other times when it al comes together. Sometimes it is very simple: an emotional leap that you have to make, and you don't think you can do it. When you succeed, it feels great. Sometimes a whole character seems to defeat you, which was the case with Nick Leeson in Rogue Trader. I thought I can't play this guy, but finally I did. "When I was making A Life Less Ordinary in Utah I became depressed. Not because of the film or the place, but just with the whole film-making process. I missed the luxury of stage rehearsals I'm tired of being asked to do emotionally risky things in front of a camera without having been given a second to get there myself. I'm tired of not being given due respect. And I'm fed up with the lack of recognition for people's creative talent. That's why it was so different working with Baz."

After the rigours of Moulin Rouge he had only two weeks off before workign on Star Wars. Continuing to play the young Jedi, Obi-Wan Kenobi was a demanding process- especially because he had to act with creations that would be added in later by special effects department.

"It was a slog but every so often during the day I would have a Star Wars moment- I'd got 'Whoopee! Star Wars! Whoopee! But it's hard to play a scene to a white wall. I can do it but it is all external stuff so how can you find the depth? Yet when it is all finished the audience will read into it what they will." The burst of boyish glee indicates that McGregor cannot believe his luck. He will return for the third installment of the prequel in two years time, giving him a meal ticket for life. He prefers making films away from Hollywood, and hasn't bee in Los Angeles for more than five years.

"It's the attitude of young actors that I don't like, and the sense of how dsposable they think we all are. I don't find that in Britain or the rest of the world:the attitude elsewhere seems more caring, " he says. "I need the support of a crew around me, but if I am surrounded by people who are falling asleep against lightstands and making mistakes because of their fatigue then I don't have them behind me. We are increasingly working in an environment where producers are working against that, and not supporting the crew and that filters through. I saw a documentary the other day about James Cagney who founded the Screen Actors Guild. He said he and his friends set it up because they were being asked to work 12 and sometimes 13 hours a day. And I was going: "You lucky bastard' because I"ve been doing 15 to 16 hours a day. And it's all down to money and producers, and there are very few truly creative ones. Now most crews are working with no overtime payments on a buy-out deal which enables producers to abuse them. You can easily find youself burning out."

He has become more adept at regulating his workload, rather than simply plunging on regardless. There have been some years when he has survived five eight-week shoots. "it's not a brilliant thing to do- to put yourself through five different characters and sets of emotions. It's hard enough just being yourself."

Moulin Rouge on release from September 7