Humphry, the fourth child of John Gainsborough and his wife, Mary Burrough was baptized on 13 April 1718. Of the four brothers, he was probably the closest to Thomas, the artist, who was the youngest child. Humphry trained as a non-conformist minister with John Eames in 1736. His first post was at Newport Pagnell in 1743 and five years later he moved to Henley-on-Thames where he remained for the rest of his life. An amateur inventor and engineer, Humphry dedicated much of his energies to various projects. These included designing a bridge over the Henley-Wargrave road, inventing a Tide Mill and a drill plow. In 1773 he helped make the Thames navigable by building pound locks and one of his duties was to collect the necessary tolls. He is also credited with with the invention of a sundial accurate to the nearest second and a perpetual motion clock. At the time of his death he was working on the development of a steam engine in competition with James Watt.
Several versions of this portrait exist, including one on a smaller scale (oil on canvas, 23½ x 19½) at the Yale Center for British Art, New Haven, which is considered the prime study (see E. Waterhouse, Gainsborough, 1966, no. 273, p. 68). Another version on a similar scale to the present painting (oil on canvas, 28½ x 23½), painted for Thomas Hall of Harpsden Hall, near Henley was sold at Christie's, London, 27 March 1981, lot 160.
Dr. John Hayes endorses the the attribution to Gainsborough stating that 'this looks perfectly authentic from the transparency' (written communication, 10 June 2003) while Hugh Belsey, also on the basis of a transparency, states 'I would shy away from a firm attribution and call it a very skilled copy' (written communication, 18 May 2003).