HEATH Ledger is contemplating being labelled as the cinema's next big thing. The new Brad Pitt, this year's Jude Law, whatever term you want to call an actor hotly tipped for big screen success.

The prediction is being made on the basis of his co-starring role opposite Mel Gibson in summer blockbuster The Patriot.

But the tanned, blond 21-year-old Australian answering questions in a London hotel room resembles a backpacker rather than a potential Hollywood leading man.

His reaction to talk about his future fame is one of amazement. "It may be interesting to you but it's really weird over here," he says. "It's really odd because I've not done anything supernatural, anything out of the ordinary. You feel that all of a sudden something or someone is out there pumping you for a reason. You feel strangely a part of that.

"I take it as it comes step by step, day by day. I don't want to worry about it or think too far ahead and wonder, 'what should I do here?'. I don't want to waste my time thinking about that."

He was given eight days off filming his next movie A Knight's Tale in Prague to go to Los Angeles, New York and London to promote the $100m movie The Patriot.

"So I haven't had time off for a bit. But it's fun and good to work hard," says Ledger, who will next star in a remake of The Four Feathers.

He's been in America only two years but already has a modest hit, the teen comedy Ten Things I Hate About You, to his credit.

He didn't work for a year before beating several hundred other hopefuls to the role of Gabriel, Gibson's son in American War of Independence drama The Patriot. He nearly ruined his chances at the audition. "I actually stood up after doing the second scene I'd prepared for them and walked out. I said, 'I'm sorry I'm wasting your time'," he recalls. "It was just not a good day. I was not in a good frame of mind to work. I knew I wasn't giving them anything good, wasting their time and wasting mine."

He must have made an impression as director Roland Emmerich, who made Independence Day and Godzilla, called him back later. He was surprised but aware he'd really have to prove himself after his first effort.

"A week later they screen tested me and three weeks later I had the role," he says. The Patriot is as much about the troubled father and son relationship of Gibson and Ledger's characters as the war itself.

Happily the pair got along fine, helping creating the appearance of a family bond. "We didn't go fishing or things like that," says Ledger. "We were instantly friends which was easy to translate into a father and son relationship. It was more of a mutual thing. We both understood how it was going to be played."

A big Hollywood star like Gibson, American-born but raised in Australia, offered a good example of how to handle the stardom people say is coming Ledger's way.

"He never sat me down and said, 'okay, son, this is how you should handle it'. You pick up a lot by being around him, by his physical presence and how he handles himself professionally and socially. If you don't learn anything from him you are blind, deaf and stupid because there's so much to learn from somebody like that.

"I was just pleasantly surprised with his attitude. I'm confident he's not changed. He's a lovely, lovely man. I guess I was blessed to work with a blockbuster actor who was down to earth and didn't let anything get to him."

To play Gabriel, he drew on his own experience although "I didn't picture my dad's head on Mel's shoulders," he says. He saw parallels between his life and Gabriel's, who joins the militia to fight the British against his father's wishes.

"I reached a stage in my life where I had my own opinions and morals and thought they were right. Because it was a new-found emotion and instinct inside me, it was exaggerated and so I took a strong stand. I was like, 'I'm going off to find it', like all teenagers do. I took off and learned some things the hard way.

"I went off in pursuit of life to discover myself as a person by discovering emotions - love, hate, pain, fear, all these things you are sheltered from in your home environment. I was discovering those through my acting profession. The same with Gabriel, whose medium of discovery was the war."

All this self-analysis makes Ledger much more serious than he actually is. He's just incredibly level-headed and clear-sighted about what he wants although he'll tell you he doesn't have any goals.

"I never expected to get here, that's for sure," he says. "I'm not looking for anything but happiness, and I have that and always have."

He misses Australia but doesn't see the point about moaning, as many do, about living in Los Angeles. He points out you don't have to go to parties or hang out with people you don't want to.

The city is "fantastic geographically" with the desert, snow and the sea within easy reach. "You don't have to live in the concrete," he adds.

Before The Patriot, he was ready to pack his bags and go home "rather than have to succumb to doing a crappy TV show or another teen flick," explaining: "I didn't want to do something I didn't like doing because, after all, I'm here to have fun.

"If I don't have a passion for what I'm doing I will do a bad job as I get bored very easily with something I don't love. I'm well aware of that. I would rather have gone home."

l The Patriot (15) opens on July 14