The Aeth family were originally from Flanders, but by the end of the 16th century had established themselves in Dartford, by which time they were known as D'Aeth. The first member of the family to achieve more than simply local prominence was Thomas D'Aeth, a wealthy city merchant closely involved with the East India company. His son, Thomas, created 1st Baronet in 1716, married Elizabeth, daughter of Admiral Sir John Narborough, who bought the Knowlton property into the D'Aeth family.
Little is known of Thomas's grandson, Sir Narborough, 3rd Baronet, the subject of the present painting. He matriculated from Christ Church, Oxford, in February 1768, aged 18 which would suggest he was born in either 1749 or 1750. He died unmarried in 1808, at which time the Baronetcy became extinct and his estates were inherited by his cousin, George William Hughes, who assumed the name of D'Aeth.
The late 1750s and early 1760s saw Reynolds produce much of his finest work. In the present painting, datable to circa 1756, the sitter is presented in a sympathetic and engaging pose, similar to that in Reynolds' portrait of Viscount Millington, painted in 1759 (see the catalogue of the exhibition, Reynolds, London, Royal Academy, 1986, p. 197, no. 35).
Sir Narborough, placed informally against a dark background, allows Reynolds to exhibit a simplicity of both composition and color as well as a freshness of handling that is typical of his paintings of this period. Without using either props or attributes commonly associated with elder sitters of similar rank, Reynolds achieves an image that is both fresh and sophisticated, in contrast to the superb but more sentimental pictures of children which he was to produce later in his career.
Dr. David Mannings in a letter dated March 15, 1997, confirms the attribution and suggests that the reason the present painting escaped mention in the standard literature on the artist may be that it was painted in 1756, a year for which Reynolds' 'sitter book' does not survive.