A three-quarter length portrait to right, wearing a black gown and his own hair. He holds his gown with his left hand and looks out of the picture space to a point beyond the viewer. His right hand holds a pair of dividers, alluding to his status as one of a famous family of ship designers and builders. He is positioned in front of dark rocks with an impression of a rocky outcrop and the sea in the distance. The stern view of the 'Sovereign of the Seas', takes up the left half of the picture.

Built by Pett at Woolwich in 1637 to the designs of his father, Phineas Pett, she was believed to be the most powerful ship of her day and was the prototype for all 100-gun English first-rates which followed, though the exact number of her guns (100 or more in her original form) remains uncertain. The ship has been painted by another hand and, if the later date for the painting is correct, it may be attributable to Isaac Sailmaker. It flies the red ensign from the stern and a St George's cross on a blue field at the main. This may bear the letters 'C R' in gold in the upper quadrants and lettering in at least the lower left quadrant, although these details are not clear. The ornately carved stern and the guns are carefully delineated, detailing the iconographic scheme for the 'Sovereign's' decorations, which combined legendary British history, classical references and heraldic symbolism. The central figure of the upper stern is a winged Victory, which was accompanied by the motto 'Validis incumbite remis' (Lean upon strong oars), not visible in the painting. Around one arm of Victory is a crown signifying riches and around her other is a laurel chaplet signifying honour. The legend 'SOLI DEO GLORIAM' (The glory only to God) can be seen above on the taffrail, which has figures of the lion and unicorn at either end, separated by the stern lantern which was said to be large enough to hold ten men. Victory's right hand points to the crowned figure of Jason holding an oar in his left hand, and the Golden Fleece over his right arm: her left hand points to Hercules holding his attribute of a club. Between these figures at Victory's feet are, on the left, Neptune on a sea-horse and, right, Aeolus, god of the winds, on an eagle. The central figure further down may be Mercury and below that are the royal arms and the three feathers of the Prince of Wales. At the turn of the quarters, on each side, are the royal heraldic devices of the rose and thistle; also the crowned monograms 'CR' and 'HM' (for Charles I and Queen Henrietta Maria) and below these a frieze of appropriate heraldic beasts - the English lion, Scottish unicorn, Welsh or Tudor dragon and the Tudor greyhound. The other friezes are less easily identified and the cartouches on the lower part of the stern are also known to have borne mottoes.

The complex emblematic programme for the ship was devised by the dramatist and poet Thomas Heywood, who did much similar work for Lord Mayors' pageants. He published the scenario before the ship was launched in 1637 with the result that, taking this picture and other images into account, more is known of the decoration of the 'Sovereign' than any other English warship of the period, or most later. The painting alludes to her dazzling quality, since Charles insisted that only black and gilt be used as colours. Each brass cannon was embossed with a rose and crown, the foul anchor, the sceptre and trident and a motto, 'Carolus Edgari sceptrum stabilivit aquarum' (Charles has firmly grasped Edgar's sceptre of the seas). This referred to the early English King Edgar, whose figure on horseback formed the ship's figurehead. Behind this on the beakhead bulkhead, six twice-life-size female figures represented Counsel, Carefulness, Industry, Strength, Valour and Victory, with Cupid bridling a lion, an allusion to the mercy of Charles I. Overall, the allegorical references promoted Charles's claim to sovereignty of the seas and naval might as a deterrent and instrument of peace. Ironically, in this context, the king's extension of Ship Money taxation to inland counties to expand his navy - including building the 'Sovereign' - was one of the causes of the Civil War that overthrew him (1642-49). The top part of the painting is probably an addition and another ship under sail has been placed on the far left of the picture.

Peter Pett was the Commissioner at Chatham Dockyard from 1647 to 1667, when he was disgraced after saving his own property before the king's during the Dutch attack on the Medway that June. The ship herself had a long career and was rebuilt twice: in 1660, when she was renamed 'Royal Sovereign', and 1685. She fought in all three Dutch wars (1652-73) and in King William's War, from 1689 until she was accidentally burnt at Chatham in 1696 while awaiting a third rebuild.

Lely, a Dutchman who arrived in England in 1641 after the death of Van Dyck, soon became his successor as leading portraitist of the day. He worked for Charles I, continued to flourish under the Commonwealth and Protectorate, and after the Restoration of 1660 was appointed Principal Painter to Charles II. In this work, the firm 1645-50 attribution to Lely (of the portrait alone) only dates to 1963. From the 18th century to 1930 the whole painting was previously attributed to William van de Velde the Elder. While he did not paint Pett, a main objection to his doing the ship is lack of evidence for him visiting England before 1660. A detailed port-broadside drawing of her is none the less attributed to him and presumed to have been done at Chatham that year, just before her first rebuild.

The painting was in the Worsley family collection at Appuldurcombe, Isle of Wight, probably from the late-17th century until it passed by marriage into that of the first Earl of Yarborough in 1806. When sold at Christie's by the fifth Earl in 1929 it changed hands three times in nine weeks; to Spink's, the London dealers, who resold it to (Sir) Bruce Ingram for £273, who then ceded it at cost to Sir James Caird for the proposed National Maritime Museum. It was Caird's first single major art purchase for the Museum after the Macpherson Collection (of paintings, prints and drawings) and before the NMM was officially created was publicly displayed in the Naval Gallery at the Royal Naval College, Greenwich. A monograph on it by Professor (Sir) Geoffrey Callender, the Museum's first director from 1934, was published at Caird's expense in 1930. This includes large-scale illustration of the van de Velde broadside drawing (currently untraced).