Flying Childers is considered the first truly great racehorse in the history of the Thoroughbred. In this, he followed his maternal grandsire (Old) Careless, who was said to be the best racehorse since his own sire, Spanker, who raced during the time of Charles II. Flying Childers was bred by Colonel Leonard Childers of Cantley Hall, Doncaster in Yorkshire, sired by Richard Darley's Arabian, imported from Aleppo, Syria around 1704. Darley kept his bay Arabian primarily as a private stallion at Aldby Park in Yorkshire but accepted a few outside mares, including Childer's mare Betty Leedes. Flying Childers raced for the Duke of Devonshire, and he won every time he started. In his own time and for long afterwards he was considered to be not only the best horse ever seen, but the best ever likely to be seen: an unrepeatable phenomenon. The History of Horse Racing by Roger Longrigg, page 54.