Sadler's Wells was a bay horse with a broad white blaze and white socks on his hind legs. He was bred in the United States by Robert Sangster's Swettenham Stud and raced under Sangster's name. Sangster was part of the original Coolmore partnership team with Tim Vigors and trainer Vincent O'Brien, later joined by John Magnier. They became active in the North American yearling auctions starting in the mid-1970s, purchasing such notable horses as The Minstrel, Alleged, Golden Fleece and El Gran Senor, the latter whom they were part breeders of, and creating a high demand for the offspring of Northern Dancer and Nijinsky. By the early 1980s, they were noted for paying millions of dollars for the right yearling, entering in bidding duels with Sheikh Mohammed bin Rashid Al Maktoum of Dubai