Played with by Humphrey Bogart, cuddled by Elizabeth Taylor and walked by Alfred Hitchcock in one of his own films, they were once more or less members of the Royal Family and among the most popular dogs on the planet.

But you'll be lucky to catch sight of any Sealyham terriers today: the breed is declining so fast that extinction beckons. More than 1,000 Sealyham puppies a year used to be registered with the Kennel Club but, in 2008, there were just 43.

Originally bred in Wales in the 19th century as a working terrier, the Sealyham appears to have become the victim of what propelled it to fame in the first place – fashion. Between the wars, and up to the 1960s, it was almost a must-have accessory for your pooch-loving celeb, especially in the movie industry. At the beginning of Hitchcock's 1963 horror film The Birds, the director, in a typical cameo appearance, is seen walking his two Sealyham terriers Geoffrey and Stanley out of a shop as Tippi Hedren (the star) walks in. Hitchcock also owned a third Sealyham, called Mr Jenkins. Cary Grant owned one called Archie Leach (his own real name) and Princess Margaret had Pippin. It was a dog to be seen with. But fashions change. "These days Hollywood stars like little continental dogs such as chihuahuas and shih-tzus in their handbags," said Paul Keevil, formerly of the Kennel Club's vulnerable breeds committee. "This is one reason why their numbers are dwindling."

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Another is thought to be animal welfare legislation which has banned tail-docking of the animals – first bred by Captain John Edwardes between 1850 and 1891 at Sealyham House, his home in Pembrokeshire, to be working terriers able to hunt animals such as rats, foxes, badgers and rabbits.

"Traditionally, soon after Sealyhams were born, their tails were docked in half," Mr Keevil said. "That was because they were small working dogs and they quite often got stuck down holes, and so they needed short, strong tails for the owner to pull them out.

"After the animal welfare legislation came into force, a lot of older breeders started to look at them differently." One of the few breeders left in Britain who is turning out pedigree Sealyhams is Kevin Holmes, 61, from Ringwood, Hampshire, who has just bred the two pictured, Prinz and Passat.

"Sealyham terriers are full of character, very loving and very dedicated to their owners," Mr Holmes said. "They are also good with children.

"People who tend to have them get them because they can remember their grandparents having one. But those sort of owners are becoming fewer and fewer as time moves on."