Frozen 2 stars: We've been practising for this since we were kids

Six years after the release of the record-breaking, Oscar-winning, ear-worming Frozen, the wait is finally over for a sequel.

Actors Josh Gad, who plays innocent snowman Olaf, and Jonathan Groff, who this time gets his own solo as Princess Anna's love interest Kristoff, told Sky News that in a way they have been preparing for their roles in the films since they were very young.

"When I was a kid, I used to sit in my bedroom alone, essentially - the sound quality is really good because it's like the bed and the stuffed animals - and I would act out all of my favourite Disney movies alone in my bedroom," said Groff.

"And the crazy revelation for me was: that is what it is like as an actor to be a voice in a Disney movie."

Gad agreed.

"That's what I equate it to also. I used to have the same experience... I had this GI Joe collection and I would basically create a movie with these GI Joe characters. And it really is like, it is the closest thing to channelling a child.

"Because your imagination has to run wild, you have to imagine everything; you're not on a set with props, with physical environments, you don't have the use of your body, you just have your voice, and so you do have to do a lot of play pretend, right?

"And I think… that's such a fascinating way to look at it because it feels spot on."

It's hard to imagine the weight of expectation when following up the second-highest grossing animation of all time - only surpassed recently by this year's reboot of The Lion King.

Groff admitted he did feel the pressure, but said it didn't last for long.

"For me personally I felt that at the very beginning of recording like, 'oh, wow, the first time we did Frozen, there was no expectation at all', and going into the studio this time thinking, 'oh, wow, this is Frozen 2, everyone knows what this is now'.

"But the minute I walked into the booth, it quickly went away because it's Chris Buck and Jennifer Lee [directors] and Bobby and Kristen Lopez [songwriters] who were the original creative team of the first movie.

"And it felt so comfortable and it felt like coming home in a way, and they were so intentional about what the story was that it's almost like once you walked into the Disney animation studio, all of the noise from outside went away and it only became about telling the best story possible."

I asked if they could pinpoint a moment when they realised just how huge Frozen had become.

For Gad it was only two weeks after the film was released.

"I was trying to get my oldest daughter, Ava, an Elsa dress, and it was like a couple of weeks after the movie came out," he said.

"And I, an actor in the film, could not find a dress, and I ran into Bob Iger, the head of the Disney Company at an event, and I said something and he's like, 'I literally had to reach out to our hotel in Hawaii', and they had like one left that he had purchased.

"Even he couldn't get it! And I was like, oh yeah, so this is a thing. That was the moment of realisation for me."

For Groff it was a little later down the line, when the film picked up two Academy Awards, for best animated feature and best original song.

"I think for me, it was the Oscars," Groff said.

"Seeing Bobby and Kristen win an Oscar, seeing Jen and Chris holding their Oscars, I was like, whoa, this has really gone to the next level."

The new film sees Elsa and Anna heading north as they look to defeat dark forces that have been festering there.

It definitely deals with some darker themes than the original, and does have a more mature feel.

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Gad believes those were necessary measures to move the story on.

"I think there's a great tradition in Disney history of never playing it safe for kids, whether it's some of the darker themes - dating back to Snow White, you know, or the tragedy of movies like Bambi and Lion King," he said.

"There's always a tendency to take kids to places, just like the early fairy tales, that helps them understand certain things in a way that's approachable.

"I also think it was very smart, a la the Harry Potter books and the movies, to age the movie with our original audience - so it's six years later, the kids who saw this movie when they were at, you know, my daughter's age, are almost teenagers now, and I think that it was important to allow them to grow with our own characters who are on a path of growth in this."

Frozen 2 is out in cinemas in the UK on Friday