Papil is a tiny township on West Burra, the final southern straggle of the islands of Burra and Trondra, connected to the Shetland mainland by bridge and causeway.

Five years ago, Harry Horse and his wife, Mandy, moved there, to a bungalow at Kulladale, just across the road from Mandy's parents, George Lamont and Grace Williamson.

The couple, whose unity and supportiveness always made an overwhelming impression, had lived in Edinburgh, Kelso and on the shores of Loch Awe, but moved to Shetland to be closer to the Williamsons as Mandy's multiple sclerosis grew worse.

Harry, whose real name was Richard Horne, cared unstintingly for Mandy, at the same time continuing his internationally successful career as an author, illustrator, political cartoonist and computer-games writer. Last Wednesday morning, a friend found the couple dead in their home. Mandy's disease had progressed rapidly. She was confined to a wheelchair and could neither walk nor speak. Harry had been suffering from depression but had written recently that the couple's life was about fighting Mandy's disease. Their cat and a dog were also found dead.

Grief and shock spread across Shetland and from there throughout the world. The hundreds of thousands of people whose lives had been touched by the art and music of Harry Horse, or by his extraordinary personality and charm, grieved the loss of a man described by his literary agent, Caroline Sheldon, as a genius.

He was born in Coventry on May 9, 1960, and educated at boarding school - at his request, his parents said last week. In the late 1970s he arrived in Edinburgh, having finished his education at Wrekin College, with a love for the banjo and a prodigious illustrative talent. One of his first published drawings appeared in the cycling magazine Freewheeling in 1979, interestingly, it was credited to Horne.

In Edinburgh, the adventure that was Swamptrash began. Harry was lead singer and banjo player, and this bluegrass-cajun-comedy-rockabilly band became legendary throughout Scotland for hilariously anarchic shows in which the band metamorphosed, thanks to Harry's introductions, into a family of white-trash American cousins.

At a time when the infamous Grand Ole Opry country music club in Glasgow prided itself on promoting the likes of Sydney Devine and gunfighter displays, Harry convinced the club that Swamptrash were genuine Americans and the band was booked to play. Suspicious, the audience and staff forced the band to adhere to a watered- down version of their masquerade, from the moment they arrived until the relieved group finally drove off towards the M8.

Swamptrash were crucial in the development of the more experimental, dance-and-dub side of Scottish acoustic music - no fewer than four former members - James Mackintosh, Malcolm Crosbie, Angus Grant and Garry Finlayson - are in the hugely successful Shooglenifty, and Harry's banjo-picking skills and love of bluegrass were passed on generously.

J J Jamieson learned banjo from Harry and went on to form the acclaimed Bongshang. Swamptrash were a live phenomenon, but never cracked the world of records. There were other bands, too, such as the later Hexology, but Harry remembered Swamptrash with the same love as many former audience members: It was the passion of his youth.

And it brought him the love of his life. In 1989, Swamptrash toured Shetland, taking the islands by storm and making lasting friends. For Mandy Williamson, then 22, and Harry it was love at first sight. The luminous beauty of the Burra lass and the Byronic bulk of Harry seemed a perfect match, and the pair were married in Bridge-End in Burra, in 1990.

Harry had already published, in 1983, Opopogo, or My Journey with the Loch Ness Monster, which won him the Scottish Arts Council's Writer of the Year award. However, it was his marriage to Mandy and their adoption of a mongrel dog from the Portobello animal sanctuary that led to his best-known work.

The little brown dog was named Roo, and became the heroine of a best-selling series of children's books, starting with The Last Polar Bears, which later became a TV film starring Nigel Hawthorne and the real-life Roo. It is thought to have sold more than a million copies worldwide. Other books in the series included The Last Gold Diggers, which won a Smarties Gold Award, and The Last Castaways. Harry also wrote and illustrated the Little Rabbit series aimed at younger children. His last book, still to be published, is Little Rabbit's Christmas.

His work has been translated into many languages and is admired all over the world, especially in the US. Financial recompense, on the other hand, was moderate, especially considering the painstaking effort put into his writing and drawing.

He was an eminent and in-demand illustrator - notably with the reclusive Jim Dodge's novella Fup - and one of the great political cartoonists, admired by the likes of The Guardian's Steve Bell. He drew for Scotland on Sunday, The New Yorker, The Guardian, Independent and latterly he was resident political cartoonist at the Sunday Herald. "We regard him as one of the most talented cartoonists of his generation," said the paper's associate editor Alan Taylor. "A highly provocative, highly talented, highly controversial artist."

Harry's other interests included writing and producing computer games such as the bestselling The Drowned God, and, of course music. When I last spoke to him, he was enthusing about a friend's musical project that involved accompanying the sound of an Arctic icebreaker's engines.

There are thousands of stories about Harry, most of them hilarious, many of them true. His ploy for getting into to see one particular newspaper editor, despite an obstructive doorman? Pretending to be said editor, and telephoning the doorman with instructions to let one Harry Horse into the building as he had arrived in Edinburgh straight from Jamaica. The "historic diaries" he carefully forged and sold to an Edinburgh bookshop, having "discovered"them. In Shetland, he made school visits to talk about his work, acted as Mandy's carer as she grew more and more disabled, and charmed all who met him.

Last year Roo the dog died ("She did not suffer, but died in my arms on her favourite place, the beach at Meal in Burra," he said). Harry spoke openly about depression, the cartoons in the Sunday Herald grew darker and darker, and last month he published a poem called Every Day is Like Sunday (after the Smiths song) quoting Schopenhauer on the right to "a freely chosen death". All his heroes, he said, were dead.