Flying Childers
Blacklegs was a bay colt bred by William Cavendish, 2nd Duke of Devonshire, and foaled in 1728. He was sired by the Duke of Devonshire's Flying Childers, who was undefeated in six starts as a racecourse. Flying Childers was also a successful stallion and was champion sire of Great Britain twice. Amongst his other progeny were the sires Blaze and Snip, along with Second, Spanking Roger and Roundhead. Blacklegs' dam was an unnamed daughter of Basto. This Basto mare also foaled the champion sire Crab, as well as the previously mentions Snip and Second. After the 2nd Duke of Devonshire's death in 1729, Blacklegs was owned by his son and successor William Cavendish, 3rd Duke of Devonshire.