This merchant captain, painted when he was eighty-two or eighty-three-years-old, is thought to be the owner of the ship in the background, since, for the purpose of the painting, his arms are on a plain blue ensign flying on the ship’s ensign staff. He is holding a rare quadrant designed by the insurance broker Caleb Smith who in 1734 designed an astroscope ‘… for taking Altitudes at Sea without a Horizon …’, and who a few years later produced his ‘New Sea Quadrant’. Smith’s instruments were made by the mathematical instrument maker Thomas Heath who was active from 1714–73. Caleb Smith’s quadrant was never very popular because it competed directly with John Hadley’s octant, invented at much the same time, and was inferior in performance.

The painting is signed in the lower left ‘R Willoughby. Pinx’ and inscribed ‘Born in 1722/Portrait taken in 1805’. A portrait painter called Willoughby, however, does not appear to be recorded, but the artist may be Robert Willoughby (1768–1843), the marine painter.

The flag on the distance ship bears a coat of arms, featuring three rudders of a ship with tillers and a red chevron with three cinquefoils. The crest above is a rampant lion resting one paw on a rudder and holding a flagstaff in the other. The motto is IN PORTU RES EST, which means 'the matter/thing is in the port' and is related to an idiom used in Latin to mean 'it is completely safe'. The arms were issued on 15 March 1790 to Thomas Reaston of Kingston upon Hull merchant son of John Reaston of Dringhoe by Alathea his wife eldest daughter of Thomas Acklom of Dringhoe Hall in the East Riding of the County of York. According to his marriage certificate, Thomas Reaston was aged sixty in 1783, making his year of birth either 1722 or 1723, which is consistent with the portrait's inscription. He died in 1807.