In 1768 Anthony St Leger (age 35) was elected MP Grimsby which seat he held until 1774.

Royal Ascot. The reign of George III. saw the institution of the " Classic " races. The Doncaster St. Leger was established by Colonel St. Leger (age 43), who lived near Doncaster. In 1776 he proposed a sweepstakes of 25 guineas each for 3-year-old colts and fillies over a two-mile course, which was won from six competitors by the Marquis of Rockingham's (age 46) filly, Allabuculia.

In 1778 a dinner was being held at the Red Lion Inn, Doncaster, on the entry day of the races, and the Marquis of Rockingham (age 46) then proposed that the sweepstakes suggested by Colonel St. Leger (age 43) two years previously should be run for annually, and bear the name of the founder. In this year it was won again by a filly, called Hollandaise, belonging to Sir Thomas Gascoigne (age 30).

In 1776 the St Leger Stakes was first run - it if the oldest and longest of Britain's five Classics which is the last to be run each year. The race is run at Doncaster over a distance of 1 mile, 6 furlongs and 115 yards (2,921 metres), and it is scheduled to take place each year in September. It was founded by Anthony St Leger (age 43) with the assistance of Charles Watson-Wentworth 2nd Marquess Rockingham (age 46).