The biggest book in Britain is The Boy, the Mole, the Fox and the Horse, by Charlie Mackesy. It’s ostensibly a children’s book, and yet it is adored by adults. Indeed, it’s been at the top of The Times of London’s best-seller list for the past six months. Since being published in October, the book has become both Waterstones’s and Barnes & Noble’s book of the year. It has been translated into 17 languages and counting. It has sold a million copies in the U.K. and the U.S. alone. Goodreads reviewers are breathless with praise for its simple koans to basic human goodness. One called it “a balm for your aching soul during the pandemic.”

“It’s very odd, because the whole book was instinctively made,” says Mackesy, a wild-haired 57-year-old. He’s been staying with friends in Oxfordshire recuperating from a torn spinal disk incurred just before the lockdown. “A lot of people were saying, ‘Well, you need more of a narrative. It’s too weird.’”

Mackesy’s debut was named both Waterstones’s and Barnes & Noble’s book of the year and has sold a million copies in the U.K. and the U.S. alone.

And yet, the book has struck a nerve like few others. Mackesy has drawn comparisons to A. A. Milne and E. H. Shepard, thanks to the sweetness and bravery of his characters, who huddle together and speak simple truths about life in uncertain times. They tell each other that dark clouds always move on, but “the blue sky above never leaves,” that kindness “sits quietly beyond all things,” that the greatest success is “to love.” Born into a world of Brexit and Trump and global divisiveness, The Boy, the Mole, the Fox and the Horse felt important on publication. Now that we have all been wedged apart by the coronavirus, it feels downright necessary.

“I think being human is universal,” Mackesy says when asked about why the book has connected. “We all have the same struggles, the same desires, the same fears. Obviously there are different nuances, but essentially we’re made the same.” What’s more, his belief in the book was total. When he met with publishers, he says, “I remember saying that if they don’t publish it well, so that it’s a treasure to hold, I will forfeit all my royalties, so they can invest in the quality of the book.”

It has been translated into 17 languages and counting.

That didn’t come to pass—the book is beautifully designed and bound—and a big part of its appeal is how precious it feels in your hands. Laura Higginson, his editor at Ebury, told me, “When we saw the paper, ink, and nibs Mackesy used to create the work, we wanted to give people that same tactile experience at home. We printed the book on the same paper Mackesy uses to draw, and sought out a printing method that gave the book a ‘just-drawn’ look.” And it works. During our chat, Mackesy spoke of the letters he’s received from people in hospices and psychiatric wards, and the nine-year-old son of his friend, who took to holding the book in bed at night after being bullied at school.

It sounds overwhelming. Does that kind of reaction feel like a responsibility?, I ask. “My responsibility is to try to respond,” Mackesy says. “I think communication is really important. I can’t heal them or cure them, but I think just the very notion that we understand each other in this difficult world is healing in itself. Particularly now, where we are. I can imagine people in their homes. Their anxiety levels going through the roof, whether it’s to do with death or tight finances or if they’ll ever see their family again. Connection is definitely the answer to it. To be able to feel that you’re not alone in this.”

Mackesy has drawn comparisons to A. A. Milne.

Once you’ve spoken to Mackesy, his book feels even more like a direct line into his soul. He’s incredibly charismatic, humming with a quietly intense sincerity, and one female acquaintance of his describes him as being “mesmerizingly attractive.… If I’d met him at a different time of my life, I just would have taken all my clothes off there and then.” You can see this charisma at work in the talks he’s given, available on YouTube, about his relationship with religion—Mackesy is a Christian who has given speeches based on the evangelical Alpha course.

Mackesy’s characters speak simple truths about life in uncertain times.

But the odd paradox about Mackesy is that despite the way he is—quiet, contemplative, wide open—he is also incredibly well connected. The book, he claims, came about after a conversation with the TV survivalist Bear Grylls. He used to attend parties with Chris Evans, a radio D.J. once notorious for his hell-raising. The two sides of him, the monk and the “It boy,” seem so far apart that surely one of them has to be a façade. And yet, according to one associate, this isn’t the case at all. “He’s the sort of chap who, whether he wants it or not, you’d probably be telling him all your secrets within 20 minutes,” she said. “He’s very easy to talk to. He’s magical.”

“If I’d met him at a different time of my life, I just would have taken all my clothes off there and then.”

What’s fascinating about Mackesy is the sense that he’s been discovered over and over again. The book has vaulted him into the publishing super league, but it came into being after Laura Higginson, the editorial director of Ebury Press, stumbled across his work on Instagram. And, prior to that, he was the in-house set illustrator for the director Richard Curtis. “We’ve known Mackesy since he was painting pavements in his 20s,” Curtis says. “When Love Actually was being shot, he offered to come down to the set to document the behind-the-scenes. We assumed he just wanted to get a good look at Keira Knightley, but the charcoal drawings he made, at great speed and with utter discretion, somehow grasped the soul of what was happening there. The joy, the boredom, the sweetness, the tension; it’s all in his blackened smudges somehow.”

There might be more books to come, or there might not, but for now Mackesy is focused on his work with caregivers. “For me, one of the highlights of my career has been the fact that the N.H.S. use my drawings on their screen savers right across the country,” he says. “They have pinned them all over the hospital walls, and they’ve hand-made postcards of the doctors and nurses, and they’ve been on pillars and school walls and people’s windows, and people send me pictures of photocopies that have been stuck on posts in villages in the middle of nowhere, encouraging people not to give up.”

This week, Richard Curtis brought a Comic Relief coronavirus fundraiser to British screens. The key piece of merchandise, not surprisingly, was a Charlie Mackesy T-shirt, illustrated with a sketch of the boy and the mole and the slogan Love Wins. It went on sale the day I spoke to him. “We’ve raised over £200,000 and it’s not even past lunchtime yet,” Curtis said. “The man is a miracle.”

Stuart Heritage is a Writer at Large for AIR MAIL based in Kent, U.K.