Frozen director reveals the biggest challenge with Frozen 2 - and key difference between the two films

"Frozen 1 we were creating new worlds, casting, finding the voices, animators are finding out how to move them and what worked, you're finding that out and exploring them," he said.

"It's staying true to the characters, but letting them grow. You have that balance staying true to her. They are their own personalities, but it's letting your kids grow up, fall, and pick themselves up. The second definitely had that kind of challenge."

In the Disney+ documentary Into the Unknown: Making of Frozen 2 we get to see the process of making the film. In one episode, Buck and his co-director Jennifer Lee both head to D23, a Disney fan event, where they showed a first look at the movie. It's also where they got to meet fans who had their own thoughts on where the story should go.

Buck said: "[There's the people's opinion to think of], because of the music, people dressing up as the characters. They really do bring the characters into their own lives. A lot of people feel they know exactly what Anna or Elsa would do or say. There's that extra pressure to stay true to the characters but also the fans think our characters should be doing too."

Buck also addressed fans calls for Frozen 3, saying that, while he hadn't even thought about it yet, to "ask [us] in six months."

He added: “After the first movie it took us about a year before we even thought about a chapter two because you are so emotionally and physically spent by the end of it – and the documentary sort of shows that, and you know it’s three to four years that kind of intensity.

“You need a break and to regroup and think.”

Frozen 2 is on Disney+ 3rd July (along with Hamilton) – you can sign up for £59.99 a year and £5.99 a month. Find out the best movies on Disney+ with our guide.

Want more Frozen 2 news? Vote for your the best Frozen song, or find out how Show Yourself was nearly cut not long before the movie's release date.