British, 1726 - 1770
Cotes was born in London on 20 May 1726. He was the eldest child of Robert Cotes and his second wife Elizabeth Lynn. At about the age of fifteen he entered the studio of George Knapton, who worked in pastel in the style of Rosalba as well as in oils. He began practice as a portraitist in his father's house on Cork Street, deriving from him an understanding of chemistry, the basis of his expertise in making pastels. Cotes' reputation was assured by the pastels he did in 1751 of the beautiful Gunning sisters, then idolized by society and the populace. His practice in oils dates from the late 1750s.
In 1763 Cotes bought the large and elegant house on fashionable Cavendish Square later occupied by George Romney, took in pupils, of whom Russell was the principal, and employed Peter Toms as his drapery painter. He exhibited each year at the Society of Artists, becoming a director in 1765, the year he married Sarah (whose parentage is unknown). Forced, as a result of intrigue, to resign along with fifteen other directors in 1768, he was responsible, with William Chambers, Benjamin West, and Mary Moser, for founding the Royal Academy of Arts. He exhibited there from 1769 to 1770. He was then at the peak of his career, patronized and highly regarded by the royal family. He died in Richmond on 19 July 1770.
[Hayes, John. British Paintings of the Sixteenth through Nineteenth Centuries. The Collections of the National Gallery of Art Systematic Catalogue. Washington, D.C., 1992: 42.]