Oil on canvas, in a painted oval, 75cm by 62.2cm.
The artist was born in Antwerp, though his family later moved to Rotterdam.
Like so many Dutch artists of the day, he moved to Italy, where he was active for a time in Venice and is known to have painted a portrait of Pope Alexander VII in Rome in 1667.
Du Bois came to England in 1680, where he was to spend the rest of his life.
He secured the patronage of the Lord Chancellor and went on to paint, amongst others, several members of the aristocracy.