If he didn't know it already (and to be honest it's rather unlikely) Jonny Lee Miller realised that the new Trainspotting sequel was going to be a big deal at the end of the first day of the shoot of the new film.

"We were filming in a basement in a pub," the English actor recalls, "and when we came out there were paparazzi everywhere. It was really weird. It was like we were filming Star Wars."

In Scottish terms T2 Trainspotting is possibly not far off. More than 20 years after the release of the original film a sequel to one of the most controversial and acclaimed British films of all time comes out next week. The original cast has been reunited and so Miller is back as Sick Boy, alongside Ewan McGregor, Robert Carlyle and Ewen Bremner.

It's hard to think of a Scottish movie for years that has so much expectation riding on it. Should we be excited? "I think it's a good movie," Miller says. "I find it hard to be objective at the moment. I've only seen it once and it's like a trip.

"I'm nervous and excited for people to see it and I feel good about it. I'm supercritical of myself personally … I hope people enjoy it. That's all I know really. I just want people to enjoy it and I think they will."

For years there has been talk of a sequel to the 1996 original but it seemed to founder after McGregor fell out with the director Danny Boyle after Boyle replaced the Scottish actor in his film The Beach with someone called Leonardo DiCaprio (you might have heard of him).

Now, though, bridges have been built, the gang is back together and presumably we can expect another movie full of sex, drugs, rock and roll. Oh and Scottish accents. (Miller, despite growing up in Kingston near London, can do Scots with the best of them.)

"It was really just wonderful to see such a nice group of people again, and really magical," Miller says. "The opportunity was not lost on anybody. We were all extremely grateful to have that opportunity and for it to be happening."

Of course the original film made stars of its main cast. McGregor did go on to appear in Star Wars movies, Carlyle turned up as a Bond villain, while Ewen Bremner became a regular in American indie movies. Miller's career was a little more wayward.

In the years in between the two Trainspotting films Miller got married to and then divorced from Angelina Jolie, and turned up in good films and bad films. And though he has now become an American TV star as a modern-day Sherlock Holmes in the series Elementary, it took him a while to really establish himself. But that was never the point, he says.

"I went off on my own life adventure, went to California and disappeared for a couple of years. I was chasing my own things. I wasn't a particularly focused individual back in the days. Nothing wrong with that, I don't think.

"As far as Trainspotting changing my life …" he adds, "I think I've said before I probably squandered a few opportunities. But I'm fine with that because everything's fine."

He lives in New York now with his wife Michele Hicks and their son Buster. "When I'm not working it's a great place to raise a kid. My son is seven years old and New York City has so much stuff for kids to do. It's a great city."

He's in New York when we speak, filming Elementary. "We've made over 100 episodes now and it's a milestone in television and we're all extremely proud of that. Lifelong friendships have been made. I've been able to put some money in the bank, buy a place to live. And all of those things I do not take for granted.

Given that he appeared on stage with Benedict Cumberbatch in a Danny Boyle adaptation of Frankenstein, (they took it in turn to play the title character and his creature) did they ever discuss all things Sherlock?

"We don't swap notes. What I was really keen to do was to try and be as different as possible as you can playing the same dude. I just didn't want to be copying him. I didn't want to be ripping him off. So I went through the books and did my due diligence and tried to put as much information as I could from the books that wasn't in other performances I'd seen and try and put it into my interpretation.

"And I've got to play Sherlock Holmes more than anyone ever has. Whether that's a good thing or a bad thing is a personal thing for the viewer. But I'm really proud of that and I like what we do with the show."

T2 Trainspotting is in cinemas on Friday.