How fitting, then, that this overgrown kid has written a children's book. High in the Clouds (with Geoff Dunbar and Philip Ardagh; Faber, £12.99) is an ecological fable about the dangers of pollution, overpopulation and urban sprawl. It concerns Wirral, a young squirrel forced out of his pristine forest home and into the filthy city of Megatropolis when bulldozers come calling. Together with a host of woodland friends, Wirral goes on a quest to find the much-talked-about land of Animalia, where creatures live in harmony, far from encroaching evil forces. In the process, he finds himself on a larger mission to liberate animals everywhere.
High in the Clouds is, in many ways, a natural outgrowth of McCartney's child-like enthusiasms, interests, and signature voice. Tunes like "All Together Now", "Maxwell's Silver Hammer" and "Ob La Di" - staples of kindergarten singalongs everywhere - bear the stamp of a charmingly innocent view of the world. Even more thematically mature songs, like "Blackbird" and "Hey Jude", are equally loved by adults and children. He credits their success with his trademark simple, easy-to-remember style.
It's entirely appropriate, then, that at a time when ageing musicians have partnered younger acts to reach the Glastonbury demographic (Johnny Cash and U2; Loretta Lynn and Jack White), McCartney is wooing the nappy set. In a sense, he has been writing for kids all his life. He has been a voracious reader of poetry and literature all his life, too. Robert Louis Stevenson's Treasure Island and the Captain W E Johns's Biggles series, he says, were childhood favourites: "They transported me from Liverpool. Cheaply." "Golden Slumbers" from Abbey Road is based on a Thomas Dekker poem. And, as he has said, "Eleanor Rigby" was patently Dickensian, while "Lucy in the Sky with Diamonds" could have been a scene from Lewis Carroll's Alice's Adventures in Wonderland.
High in the Clouds is a rich, meandering, often funny tale. While the illustrations feel somewhat wooden and the ending slightly pat, young audiences will delight in the clever wordplay and smartly-drawn comic characters like Alfredo, the weightlifting flea. The story abounds with literary references: an allusion to James Herriot's All Creatures Great and Small, a fat, bowler-hat-clad rat named Wackford (after the eponymous headmaster from Nicholas Nickleby), and an animal assembly scene straight out of Kipling's The Jungle Book.
But McCartney has no ambitions to become the next Beatrix Potter. High in the Clouds is just the latest in a long line of artistic projects to flow from his apparently limitless imagination. He is uniquely equipped to write for children, however, given his live-in focus group: his two-year-old daughter Beatrice, who, he says, loves the pictures but is too young for the words. And although High in the Clouds ends with the rather quixotic "The End/ Of the beginning," McCartney has no plans for a sequel - although a feature-length film based on the book is on his radar. Nor does he see himself as part of the growing pantheon of celebrity children's book authors such as Madonna, Julie Andrews and Sarah Ferguson, since this project actually began ten years ago - as a song.
The story and many characters are drawn from "Tropic Island Hum," a song McCartney wrote in the late Nineties. Later, he developed it into a short animated film with Linda and his long-time collaborator and friend, Geoff Dunbar. McCartney and Dunbar first joined forces in the early 1980s on the animated short Rupert and the Frog Song. Their Daumier's Law picked up a British Academy Award and Director's Choice Award at Cannes.
The pair had always dreamed of turning Tropic Island Hum into a feature-length film, so to focus ideas and pique producers' interest, they decided to create a one-off mock-up of a book. McCartney turned to Suzy Jenvey, who heads the children's division at Faber, which published his verse collection Blackbird Singing. She helped flesh out the story, saw its potential, and suggested a book. "We got pretty excited," McCartney recalls, but he felt the writing was weak and wanted someone who could lend it more grace.
Enter Philip Ardagh, author of the darkly comic and much-lauded Eddie Dickens trilogy. The two clicked immediately. When McCartney saw Ardagh's revised first chapter, a creative triumvirate was born. His " page-turning, humorous style," says McCartney, "had a command I was looking for. You see and feel it immediately, from the first page."
McCartney admired Ardagh's ability to make the story sing and to show instead of tell. "Whereas I would have written, 'Once upon a time there was a squirrel called Wirral'," says McCartney, quoting the opening lines, "Ardagh opened with 'Wirral the squirrel was lying back on a branch, munching acorns from a bag as he listened to his mum telling one of her stories'." The collaboration was ideal. "We have an easy working friendship. We tended to just like the best idea. Which was always mine." Pause for effect. "I'm kidding," he says, grinning broadly.
McCartney and Dunbar would meet weekly to hatch ideas. McCartney would act out the characters and Dunbar would draw. "I would say, 'he talks like this'" - lowering his voice to mimic the snarl of a bullying badger - "or 'he's a bit like this'" -stretching his arms to imitate the generous girth of a bison. Then, the pair would turn over the week's work to Ardagh, who would tweak the words and flesh out the characters. All three share the authorial credit although, at one point, Faber suggested that only McCartney get cover billing. "Are you kidding?" he said. "This was a team effort."
The story is filled with idyllic nature imagery that wouldn't feel out of place in a Dylan Thomas poem, but it doesn't shy away from darkness. The city, Megatropolis, is pictured as a rubbish-strewn hell full of " hungry, dirty and desperate" inhabitants with "dull eyes". Animals toil in a factory under abhorrent conditions. In a poignant scene, the young squirrel protagonist buries his mother. Not exactly Teletubbies.
That's precisely the point, says the author. The world is a scary place. The factory, he says, is based on the former sweatshop practices of clothing chain GAP. In the book, a giant "G" logo is emblazoned on the factory wall. Gretsch, the foremost evil force, could be a stand-in for George W Bush, whose anti-environmental stance upsets McCartney. "When our grownups are people like George Bush, who needs grownups?" He asks. "Not me."
McCartney thinks that kids need to know certain things about the world. That "knocking down a forest is a bad thing... and that sweatshops are a bad thing. Anti-cruelty, anti-oppression - it was always important... to infiltrate with those messages." The trick to effective infiltration, though, is slipping the message by children, so they don't know there is one. Kids, he says, have to feel that they're "just reading a story," not being preached to.
McCartney has been promoting green values most of his life. As an activist and outspoken vegetarian, he has been linked to countless environmental causes, both with his late first wife Linda (Eastman) McCartney and current wife, Heather Mills McCartney. Whatever the medium or message, McCartney is a storyteller whose stories appeal to the child in all of us. His shows are often packed with youngsters, he says. That cross-generational appeal was the inspiration behind the name of the current tour : US.
On the cover of Chaos and Creation, there's a photograph of McCartney as a boy, strumming a guitar at home in Liverpool. Whether he's writing songs or children's books, that boy is ever-present. Miraculously, he never went missing. "Childish?" he ponders. "Yeah. I hope I am. I wouldn't want to lose that."
Paul McCartney was born in Liverpool in 1942. In 1957 he joined the band The Quarry Men, which eventually became The Beatles. His first solo album, McCartney, was released in 1970, two weeks before the Beatles' final album, Let It Be. Throughout the 1970s he released, with his late first wife, Linda, albums with Wings. Solo albums since have included Pipes of Peace, Liverpool Oratorio and, most recently, Chaos and Creation in the Back Yard. His books include Wingspan, a personal record of Wings, a memoir (with Barry Miles), Many Years from Now, a collection of his paintings and a book of poetry, Blackbird Singing. His children's book, High in the Clouds, is published by Faber & Faber. Paul McCartney was knighted in 1996. He lives with his wife, Heather Mills McCartney, and their two-year old daughter, Beatrice.