Russian Blue
After the war, in an attempt to maintain the breed standard, the GCCF decided to accept only third-generation Persian/British Shorthair crosses. This contributed to another shortage of pure breeding stock by World War II, at which point the Persian and Russian Blue were reintroduced into the mix. British Shorthair breeders also worked with the French Chartreux, another ancient breed, which although genetically unrelated to the British Blue, is a very similar cat in appearance. Breeders worked to re-establish the true British type, and by the late 1970s, the distinctive British Shorthair had achieved formal recognition from both the Cat Fanciers' Association (CFA) and The International Cat Association (TICA). According to the GCCF's 2013 registry data, it is once again the most popular pedigreed breed in its native country.