Hair apparent: Welcome to the compelling world of competitive 'Cavy fancy'

The peruvian is noted for its soft coat. The cuteness of the Crested, with its cranial tuft and round body, can floor even the most hardened of judges. The Self Saffron, on the other hand, boasts fur like burnt amber. Each breed has its unique traits. But perfect looks don't come easy.

Make sure you prepare early. Thoroughly wash your animal. Clip its nails. Long-haired varieties demand special attention – to shampoo, or not to shampoo? And then there's that enviable sheen. Some fanciers have a secret weapon. They cover their pet in vinegar. That's a trade secret – please don't spread it around.

If you thought Crufts was tough, then sneak a peek at the world of "cavy fancy", the competitive showing of guinea pigs. It's a big deal in the world of tiny pure-breds: there are around 1,000 fanciers in Britain participating in an average of six cavy shows every week around the country. This guinea-pig-eat-guinea-pig world of cut-throat contests stretches from Aberdeenshire to Cornwall, with breeds assessed on health, size, shape, colour, length and quality of coat. Competitors vie for prize money, rosettes and cups – but it's mainly the prestige that they're after. "People like the challenge of trying to work with nature to produce an animal which is as near to perfection as they can make it," says British Cavy Council chairman Bryan Mayoh.

Last year, the photojournalist Hazel Thompson took a break from reporting on the Middle East to follow champion exhibitor and show breeder Margaret Hooper. The photographer recorded Hooper's care for the 80 cavies she keeps at her family home in Swindon, as well her involvement with the Wiltshire Cavy Club, where she helps organise three shows a year. Hooper even helps man a "cavy helpline" supplying telephone advice to fanciers seeking succour over grooming or health issues.

"I wanted to do something for light relief," laughs Thompson. "The Disney film G-Force, which follows guinea pig secret agents, had been released, so it was on my mind. I'd kept guinea pigs as a kid, and seen them competing at country events. It was quirky, and was a different side to British culture we don't ordinarily see."

Guinea pigs hail from South America, where they are still eaten as a delicacy, and were first introduced into Britain around 1500. Queen Elizabeth I is thought to have had one, but it wasn't until the 1890s that guinea pig fancying properly took off. The Bradford Championship Show, now held in Harrogate, was founded in 1921, and has become the biggest cavy event in Britain, closely followed by Reading's "London Championship". Each show can have as many as 1,000 participating critters, competing in categories separated according to breeds.

"I was surprised by the diversity of people showing," adds Thompson. "From eight-year-olds to housewives who do it as a hobby – I enjoyed meeting this gamut of eccentric characters. Some people were surprisingly trendy – there seems to be a fashion for it coming from Sweden. And there were quite a few young gay men. Everyone takes it very seriously: the grooming process is stringently adhered to. Many of the top breeders have 80 to 100 guinea pigs living in sheds outside their houses."