Lely was born Pieter van der Faes to Dutch parents in Soest in Westphalia,[4] where his father was an officer serving in the armed forces of the Elector of Brandenburg.

He is reputed to have adopted the surname "Lely" (also occasionally spelled Lilly) from a heraldic lily on the gable of the house where his father was born in The Hague.

He arrived in London in around 1643,[5] His early English paintings, mainly mythological or religious scenes, or portraits set in a pastoral landscape, show influences from Anthony van Dyck and the Dutch baroque.

As Brian Sewell put it: There may well be thousands of these portraits, ranging from rare prime originals of often quite astonishing quality, to crass workshop replicas by assistants drilled to imitate Lely's way with the fashionable face and repeat the stock patterns of the dress, landscapes, flowers, musical instruments and other essential embellishments of portraiture.

He was replaced as court portraitist jointly by John Riley and Sir Godfrey Kneller, also a German-born Dutchman, whose style drew from Lely's but reflected later Continental trends.

He painted both men and women, but with a greater inclination towards the latter, whose cleavage was often accentuated, sometimes to the point of having one breast fully exposed (such as in Margaret Hughes's earlier portrait, seen below).

[citation needed] The loss in 1929 of a "family portrait by Sir Peter Lely" was reported in the fire at Pit House, Farley Heath, Albury.