Morier was a Swiss military and sporting painter who started working for William Augustus, Duke of Cumberland (1721-65) in 1747, when he painted a series of pictures of troops under his command. From 1752 until 1764 he was employed as ‘limner’ (painter) to the Duke on an annual salary of £100; his name also appears regularly in Royal accounts from 1764 to 1767.

The sitter was previously identified as Frederick, Prince of Wales, which does not appear correct. He is shown mounted on a white horse riding to the right, wearing a blue coat with silver details and holding a sword in his right hand. 

To the right is a 'runner', a servant responsible for carrying messages and running in front of his master's horse or carriage to clear the way. He carries the ceremonial staff of the role and wears the livery typical of such a position - a short jacket without tails, a fringed skirt and a tasseled sash around the waist, with light shoes designed for speed. His short cap is ornately decorated with the heraldic device of his master. Here the rider is probably a member of a German princely house and colonel of the cavalry regiment shown in the background.