Archie, the pet dog who inspired a bestseller, 'snatched from outside shop' Ms King, from Hampsted, said: "I felt awful. It was my worst nightmare because I don't usually leave Archie outside. My partner or I usually stand with him, but it was just a quick thing. I'd just picked him up from the dog sitter and we'd been for a walk on Hampstead Heath and I thought, 'You're being stupid, there are other dogs out here.' It's the worst thing. She added: "You can't just steal a 13-year-old dog, it's a responsibility to have an old dog. Archie's a real terrier - he's got a strong will and personality. Archie was tied to railings outside M&S when he was stolen between 5.15pm and 5.35pm. Staff are helping police and the store's CCTV footage will be studied as officers hunt the thieves. Archie is connected with a family who have lived in Hampstead for half a century and he originally belonged to Ms King's mother-in-law, artist Rosie Harrison. When she died Archie went to live with her daughter, actor and director Trilby James, 49, and her civil partner, Ms King. Archie also inspired the character of a dog in author Sita Brahmachari's book Artichoke Hearts, which won the Waterstones' Children's Book Prize in 2011. Norfolk terriers can be worth up to £500 when at breeding age but it is thought frail Archie is unlikely to be valuable at 13.