Back To The Future star Christopher Lloyd has said he remembers being "unsure what he was doing" while making the classic film.

The veteran actor, 82, is best known for playing Doc Brown in the trilogy of movies about Michael J Fox’s teenager Marty McFly, who travels back in time using the eccentric scientist’s time machine.

Arriving at the opening night of the new musical stage show of the 1985 film in London, Lloyd said: "It just keeps moving along, it’s indestructible.

"I just hoped it would have a good opening and a nice run, and it’s still running."

Cast member Mark Oxtoby and Christopher Lloyd bow at the curtain call during the opening night performance of "Back To The Future: The Musical" at The Adelphi Theatre

Assessing the film’s enduring appeal, he said: "It’s a family story, Marty and his brother and sister and mum and dad. And it’s time travel.

"Everyone thinks about time travel, thinking ‘Gee, what would it be like to be there?’"

Reflecting on his memories of making the film, he said: "I was unsure what I was doing.

"They changed the casting in the sixth week and my first feeling was ‘oh my god I’ve got to do that again’. But then Michael came and nailed it."

Robert Zemeckis, who directed the film and co-wrote the screenplay, said: "(A musical) is something I never imagined was going to happen.

Christopher Lloyd and Michael J Fox in Back to the Future

"I would like to hope it’s because the story is really well told but I don’t really know how this story has captured the imagination of so many generations.

"I think the story is universal, I think that there is something about wondering what your parents were like when they were your age is universal.

"Truth be told, I’ve seen the show already in Manchester and it’s fantastic, it’s just brilliant. It brought a tear to my eye, it’s the perfect companion to my movie.

"It’s not a recreation of the movie in an exact way, the characters are there in spirit but they are not the exact same characters and they don’t try to be. It’s his own creative entertainment entity."

Sharing his own memories of making the movie, he said: "It was a very chaotic time, there was a lot of chaos, that is what I remember."

Back To The Future: The Musical is now open at the Adelphi Theatre in London

Source: Press Association