Southdown sheep wool and cereals due to rising volumes of imports from the British Empire was accompanied by the Wet Years - a six-year period of cold, wet weather with little sun. In the Second World War, the South Downs were commandeered for military training, only fringe farms being left to produce milk for the towns. Sheep farming declined further after the war, although it is now being encouraged again through the designation of the downland as an environmentally sensitive area, and the restoration of arable land to sheepwalk. The Southdown has been placed on a watch list by the Rare Breeds
Breed registry stud book is a stud book or breed registry that does not accept any outside blood. The registered animals and all subsequent offspring trace back to the foundation stock. This ensures that the animal is a purebred member of the breed. In horses, an example of a closed stud book is that of the Thoroughbred, with a stud book tracing to 1791. The American Kennel Club is an example of a kennel club with primarily closed books for dogs; it allows new breeds to develop under its Foundation Stock Service, but such dogs are not eligible for competition in AKC