Simon (Jonny Lee Miller) and Mark Renton (Ewan McGregor) in T2: Trainspotting.

His appearance alongside Kerry Fox in Danny Boyle's directorial debut Shallow Grave, unearthed Ewan McGregor's raw talent. But it was his hypnotic, drug-addled portrayal of Mark Renton in Boyle's follow-up smash, Trainspotting, which catapulted McGregor from unknown wannabe to fully-fledged celebrity.

Trainspotting was a runaway success - a beguiling, bruising tale of heroin highs and comedown lows which chillingly exposed the seedy, urban underbelly of the drug and club culture in 90s Britain. It also unleashed one of the most iconic monologues in cinematic history, with McGregor's infamous "choose life" rant perfectly capturing the pre-millennial zeitgeist, becoming a global rallying cry for disenfranchised youth.

It's an adage McGregor seemingly embraced, judging by the way he seized upon his newfound notoriety to ride Trainspotting's tsunami of success to even greater Hollywood heights, including starring roles in Velvet Goldmine, Emma, Moulin Rouge and the Star Wars prequels, as Jedi knight Obi-Wan Kenobi. He hasn't looked back since.

"I think I've always grabbed life by the balls," McGregor surmises, smirking at his intentional double-entendre. "I don't think I was guilty of not doing that before Trainspotting, but that "choose life" scene definitely accentuated the feeling because it was a powerful piece of writing and I was very moved by it.

"It's something that's very identifiable with Trainspotting. That's why we brought it back - and updated it - for this film," he adds, earnestly. "I loved the conceit of doing that speech again and how we've changed it from a voiceover last time to me saying that to another character this time, with those lines pouring out of me. I think it makes it a very funny, poignant scene."

Resurrecting such a pivotal slice of Trainspotting lore presented some challenges though, as McGregor explains.

"It's a beautiful piece of writing and I love the way it flows, like a poem," he enthuses. "It deserved to be said correctly, so I made sure I learnt it perfectly because I didn't want to screw it up. Thankfully, I eventually managed to say it all in one go and get it completely right - although it took me a few takes to do that."

McGregor's trademark tirade is just one of many parallels between Trainspotting and t2. Accordingly, it's again set in Edinburgh and features Johnny Lee Miller as Sick Boy, Robert Carlyle as Begbie and Ewen Bremner as Spud, alongside McGregor's character. But this time Renton is returning home to try to make amends with his former friends, rather than running away after swindling them.

However, their would-be reunion is fraught with recriminations and reprisals, then reconciliation and redemption, which ensures T2 is another slice of film noir, albeit more nostalgic and reflective than its hedonistic, iconoclastic predecessor.

"Renton suffers a heart attack and as his world is falling apart, he realises that he has no-one to turn to and nothing of meaning in his life where he's living, in Amsterdam," says McGregor, explaining the more sombre tone of t2. "So he returns to Scotland, the only place he feels any connection with, to the security and familiarity of his roots.

"Going back to Scotland, where I haven't lived since I was 17, and getting back together with everyone again, was very emotional. You couldn't help but be touched by it," adds McGregor, thoughtfully.

"Making Trainspotting was a once-in-a-lifetime experience because everything about it was amazing - the subject matter, the actors, the cinematography, the sets and the music. The feeling we created, knowing we were making something extraordinary, was just incredible. So, for those reasons, looking back on that and then playing these characters again 20 years later made us re-examine our own youth and feel very nostalgic."

McGregor also admits that reprising his most memorable role was an incredibly daunting experience.

"Renton is such an iconic Scottish character, so I really did worry about playing him again after such a long time. After all, it is an odd, unique situation to play somebody that you last did 20 years ago! There's no book that tells you how to do that," he says, laughing.

"At first, I really didn't know how I was going to manage it.

"I remember the first day I arrived on set, I met Ewen Bremner in the lunch queue and I said to him; 'I'm quite nervous about this'. He admitted he was nervous too, but assured me that we'd be fine when we started filming. And we were," recalls McGregor. "But I think we felt that way because this film meant a great deal to all of us and we were anxious that we didn't f*** it up!

"Luckily, the moment I began playing Renton again a lot of the elements of his character came straight back to me. I think it's because we're very much alike," McGregor surmises. "There was something very easy about it, so I needn't have worried."

"You know, working with all these guys again, especially Danny [Boyle] after such a long time, was really special," he says. "I was as happy as I could be to be back on his film set. I loved working with him in the past - I think he's one of our greatest filmmakers today - and I loved working with him again now. It was great, it was like coming home."

LOWDOWN:
Who: Ewan McGregor
What: the sequel to Trainspotting, T2
When: in cinemas next thursday