Illustrator Charlie Mackesy on seeing his book come to life on screen

The biggest selling adult hardback of all time earned British-born illustrator Mackesy a short film adaptation that promises the same magic on screen.

Reimagined in full colour with hand-drawn traditional animation, the BBC One special will take audiences on a poignant journey this festive season, as the foursome unite in the boy's search for home.

Breathing life into the book's protagonists is an award-winning cast of actors including Tom Hollander as the mole, Idris Elba as the fox, Gabriel Byrne as the horse and newcomer Jude Coward Nicoll as the boy.

It's a line-up Mackesy, 59, still finds hard to fathom. "It blows my mind that I'm sitting here talking about a film which began with drawings, with little thoughts or fears, hopes, aspirations or dreams, that seemed to speak to people," says the artist and author.

"But here we are and I'm very grateful to everyone, however they contributed."

So what else can he tell us about his journey to screen?

WHAT WAS YOUR INSPIRATION BEHIND THE BOOK?

To be honest, it was instinctive and not too conscious or objective. I didn't have a brief or an ambition. It was just on a daily basis, questions that arose, that these characters would have. I would WhatsApp friends and ask, 'What do you think?' And so it was more of a conversation, not a narrative. There were other creatures in the mix - a polar bar, penguins, koalas - but these four seemed to settle visually and their characters seemed different enough and worked together. I'm saying this like I knew what I was doing, and I didn't.

AND THEN THE OPPORTUNITY FOR A FILM CAME ABOUT. HOW DID YOU FIND THE PROCESS?

It was a baptism of fire. It was a journey, hours a day on Zoom. We had collaborative talks: How do they move? How do they look? How do they sound? Everything was up for discussion. It was just making a cake that none of us had ever made before, with ingredients that were new. And so, the cake took time. And I think I was quite probably quite difficult.

HOW DID IT FEEL TO SEE THE CHARACTERS COME TO LIFE?

I never really imagined (how they moved). I remember watching YouTube clips of penguins at 2am and in the morning saying, 'The mole walks like a penguin!'. The rest of the characters referenced real life, so that was easier. My real journey was having to mark the animators' work and send it back saying 'Could do better'. I felt like a grumpy schoolmaster. But eventually I saw how this entire, brilliant team had learnt a language that we all speak now, in terms of movement and line. It was a learning curve for all of us.

WHEN WRITING, DID YOU HAVE DISTINCT VOICES FOR EACH?

The boy's voice had always been a soft Scottish accent. So when I heard Jude Coward Nicoll, I said, 'Well that's him then'. There was something about the innocence and the tone of Jude's voice. Tom [Hollander] had always been in my head as the mole - I love Tom and his voice sounds like a cake. And the horse had always been Irish, so Gabriel [Byrne], I remember I had a call with him and before I said anything, he said, 'Charlie, I am the horse'. What a dream to have him, that depth. I like dangerous voices that become kind.

YOUR WORK IS LOVED GLOBALLY - HOW DOES THAT MAKE YOU FEEL?

On Instagram, I'd post a drawing and get a reaction from a hospital, saying, 'Can we just stick this on the wall?' or the Army: 'Can we use this for our guys when they come back from fighting, to tell them it's OK to feel that stuff?' So I found myself caught up in a journey with a lot of other people who have all contributed to the book. And to the film. I love the co-ownership of it. I love the fact that schools have made their own versions of the book and that they had the drawings on their walls during the pandemic. All of that stuff moves me so deeply, to think that it began with a strange person in a little room but then his drawings were taken on by others. It's such a relief because I'm not clever enough or good enough to do it on my own.

DID YOU EVER ANTICIPATE YOUR WORK WOULD HAVE SUCH AN IMPACT ON MENTAL HEALTH TOO?

(Mental health) is something I have struggled with. My drawings were an honest, vulnerable dialogue that addressed some things. When I did get a reaction from clinical psychology hospitals, I remember thinking, 'Really? OK. That's great'. I didn't think I would achieve that. I remember being at a book signing, one of the first ones, and there was a longish queue, and a boy was standing very quietly and looking at me. He had a book, I signed it, and he just said, 'I just want you to know that your drawings have helped me stay'. I wasn't quite sure what he meant by the word 'stay' and he said, 'I'm still here'. I remember thinking, 'Oh my gosh, if this helps one person, I'll take that'. This 18-19-year-old boy is still around because of drawings I scratched out.

DO YOU HAVE PLANS FOR A SEQUEL?

I feel there's a lot more to say and there are other characters who they would meet and interact with. I'm quite into the idea of obsolescence. I remember a lady saying to me, years ago, 'I remember the day that I became invisible'. I thought I could relate that to a polar bear, who may start to feel the danger of obsolescence. Just the idea of the environment - have we ever talked about that from an emotional perspective? From a creature? Rather than just, 'This has happened'. So I hope we have more to say.

The Boy, The Mole, The Fox And The Horse airs on BBC One this Christmas.