For the men and women who own Britain's 11,000 racing greyhounds there's a dream of winning a fortune in prize money and gambling. Some pin their hopes on a single dog cosseted at home as one of the family, fed on a secret diet and trained when few people are about. Others kennel 70-80 dogs in the expensive hope of finding a world-beater among them. Some use professional trainers. It's exciting, heartbreaking and sometimes shady. It draws bigger crowds than horse racing, attracts more gambling money than the football pools, and it's split under two codes. One is governed by a 146-page rule book; the other is an unwritten, free-and-easy game of bluff and counterbluff. Harold Williamson has been with the dogs, the owners, the winners and the losers.