Sleeping Partner (foaled 1966) was a British-bred thoroughbred racehorse and broodmare. She showed modest form as a juvenile in 1968 but developed into a top class performer in the following year, winning the Lingfield Oaks Trial, Epsom Oaks and Ribblesdale Stakes. She did not win again and was retired from racing in 1970. She produced no known foals. Background Sleeping Partner was a grey mare bred in England by her owner Harry Primrose, 6th Earl of Rosebery. She was sent into training with the veteran Jack Jarvis at his Park Lodge Stable in Newmarket, Suffolk. Unlike many greys Sleeping Partner was very light in colour from a young age and appeared almost white during her track career. She was sired by Parthia, who won the Epsom Derby in 1959 but was a disappointment as a breeding stallion in Europe before being sold and exported to Japan in 1968. Her dam Old Dutch won two races at Newmarket Racecourse and was a half-sister of the Ebor Handicap winner Donald. She was a great granddaughter of the British broodmare Pearl Maiden (foaled 1918) whose descendants included numerous major winners including Pearl Cap, Pearl Diver, Molvedo, Niniski and Belmez. Racing career 1968: two-year-old season Sleeping Partner raced seven times as a juvenile but was slow to mature and showed stamina but little speed. She recorded her only success in a maiden race over seven furlongs at Ayr Racecourse in September, but did finish second on at least three occasions. In his last phone call to Lord Rosebery, Jarvis said "Don't be surprised if I win the Oaks for you this time with Sleeping Partner". When Jack Jarvis died in December 1968, the five-time champion jockey Doug Smith took over the training of the horses at the stable, with the 23-year-old Michael Stoute as his assistant. Stoute later recalled "Some of the staff we inherited were in their 80s. Jack couldn't bring himself to retire them". 1969: three-year-old season Sleeping Partner made her first appearance as a three-year-old in the Oaks Trial at Lingfield Park Racecourse on 17 May and won at odds of 14/1. In the 191st running of the Oaks Stakes over one and a half miles at Epsom Racecourse on 7 June the filly was partnered by the South African-born jockey John Gorton and started at odds of 17/1 in a fifteen-runner field. The leading contenders appeared to be Full Dress