Hayls may have trained in The Hague or Amsterdam with the Dutch portraitist Michiel van Mierevelt and by 1651, had visited Rome. He was active as a portrait artist in the 1650s and 60s, and by that time, ranked among Britain's most important artists. Hayls is frequently mentioned in the Diary of Samuel Pepys, who also commissioned the artist to paint a portrait of his wife as Saint Catherine (now lost) and a portrait of himself.
