A half-length portrait to left in captain's full dress uniform, over three years, 1748-67, with the sitter's head turned to look out at the viewer. He holds a telescope in his left hand and his ship is in the distance on the far left. The painting is a 19th-century replica of a portrait painted in 1766-67.

Ferguson was promoted rather late to lieutenant in 1756 and went as flag captain to Admiral Lord Colville on the North American station in 1763. During the American Revolutionary War, 1775-83, he served almost throughout on the American and West Indian stations. In 1784 he became Lieutenant-Governor of Greenwich Hospital. There is also a portrait of his wife in the collection, see BHC2689.