Tom Fletcher's book 'The Christmasaurus' is being made into movie

The 'Obviously' hitmaker announced the news during the launch for the novel, and revealed that Michael Gracey was on board to direct the project, although he was too busy filming his latest movie in New York and so couldn't make it to the event.

Instead, appearing in a video message, Michael spoke about his involvement with the film before the video was gatecrashed by his 'The Greatest Showman' stars Hugh Jackman and Zac Efron.

Hugh told the camera: "The songs are great, I've heard them. They're very catchy."

After the launch, the 'Love Is Easy' musician said he was "really lucky" to have Michael on board, and thought it was "so cool" that he had Hugh Jackman's approval.

He said: "I couldn't believe that, it's so cool. Michael was meant to be here today but everything has gone rapidly for him so he couldn't be, but it's okay... If you have to be somewhere else than filming with Hugh Jackman and Zac Efron is a good excuse. He's an incredible director, so we are really lucky to have him on board."

And the star - who has two sons, Buzz, two, and Buddy, seven months, with wife Giovanna - admitted it had always been his plan to make 'The Christmasaurus' into a movie, but wanted to write the book first in order to retain creative control.

He said: "I love writing, so my natural place to go is to a book because I am in charge of it. Making a film requires many more people on board, so when I have ideas for stories - even though I can see them as a film - I tend to write them as a book first because you get your vision into it. If you have a real passion for it you feel like it's your baby, it's really difficult letting it go."