Pastel portrait of Captain William Pierrepont, shown three-quarter length, half turned to viewer's left on board ship, with a telescope under his left arm, in captain's (over-three-years) full-dress of 1795-1812. His hat is just visible on the quarter-deck rail (left) with the hammock nettings and open sea behind, and the picture is signed lower left 'J. Russell pinxt / 1801'. It is a pair with that of his wife, PAJ2906, of the same date.

William was apparently the third and probably second surviving son of Charles Pierrepont (d.1788) and his wife Mary, of Uffington, near Stamford, Lincs. He was almost certainly born there and was baptized there on 4 March 1766. A brother, Charles, was also baptized there in June 1762: another, Michael, born there on 1 November 1763, died as a considerable landowner in Rutland in 1834. Commissioned on 2 December 1789, William served as fourth lieutenant in the 'Leander', first in the 'Inconstant' and third in the 'Boyne', before being given command of the cutter 'Seaflower' by Sir John Jervis in his and Lieutenant-General Grey's West Indies campaign of 1794 at the start of the French Revolutionary War. He rose to commander on 19 May that year, then post-captain on 4 August in the 'Brilliant' and 'Blonde' (1794-5) before appointment to the new 38-gun frigate 'Naiad' in April 1797.

On 23 April 1798, she and the 'Jason' captured the gun-vessel 'Arrogante'. 'Naiad' then took the French privateer 'Tigre' on 11 August and on the 22nd sighted the French 'Le Decade', 36 guns - but mounting only 26 - under Captain Villeneuve, making landfall off Cape Finisterre from Cayenne. An all-night chase brought her to action late next day in the Bay of Biscay, with the 'Magnanime', 44 (Capt. the Hon. Michael de Courcy), joining in the offing. After an hour's fight Villeneuve surrendered to 'Naiad' alone.

In March 1799 'Naiad' took the 20-gun French privateer 'Heureux Hazard' off the Loire and on 15 August, still on patrol in the Bay of Biscay, sighted and gave chase to the Spanish frigates 'Thetis' and 'Santa Brigida' (both 34s) inward bound from Mexico with £600,000 of treasure, mainly Mexican silver. The following day three other British frigates, 'Ethalion', 38, 'Alcmene' and 'Triton' (32s) joined in. 'Ethalion' brought 'Thetis' to action north of Cape Finisterre and took her. 'Triton' briefly ran aground pursuing 'Santa Brigida' south of the Cape but, with 'Alcmene', captured her there after an hour's action. All three ships, and the supporting 'Naiad', were then among rocks but succeeded in getting clear. The prizes were taken into Plymouth on 21 - 22 August. Each of the four captains' share of the treasure and sale of the Spanish vessels (not taken into the Navy) was £40,730 -18s. Even individual seamen and marines got just over £182 each: these were huge sums at the time, the captain's shares being worth more than £8 million each in modern terms, and the whole being one of the Navy's most valuable captures ever at sea. The Museum also has a covered silver tankard by William Pitts incorporating coins from the treasure (PLT0169). Pierrepont may have commissioned or owned this, since it was certainly later owned by his son Henry.

Pierrepont's health took him ashore in December but he commanded the 'Dedaigneuse' in 1801 and 'Zealous' in 1807. He may also have briefly commanded Sea Fencibles at Liverpool in 1803. In 1800 he bought Shalford Manor, near Godalming, Surrey, and in 1801 the nearby Farley Hill (later Unsted Park) estate, Bramley, from fellow Captain Albemarle Bertie, who moved to Nether Hall, Suffolk. He had married Maria Salter in 1797 but of their five children born at Farley Hill only two reached adulthood, though all were still alive when he died there, aged 46, on 7 August 1813. He was buried in a new vault in St Peter and Paul's churchyard, Godalming, on the 16th, and there is a fine monument to him in the church on which the names of third and fourth children (who died early in 1814) are also inscribed.

He had risen by seniority to Rear-Admiral of the Blue on 12 August 1812, and had by this time further added to his Farley Hill land. His will, made in 1806, put his estate in the hands of three trustees, comprising from 1807 Captain Robert Jackson RN, his naval agent James Halford senior, and his solicitor, with instructions to sell it to establish funds for the maintenance of his family. It was sold in July 1814 for just over £18,800, after which his widow and three surviving children moved to Bath where their eldest son, William, also died in 1819 and their first child, Anne, married in 1823. His wife died at Bath in February 1864, only their youngest child, Henry, surviving her.

After his master, Francis Cotes (d.1770), Russell was the leading English pastel portraitist of his time and also a notable amateur astronomer, especially interested in the Moon, of which he devised a remarkable scientific globe called the 'Selenographia': of this the Museum has one of the few known examples (GLB0140). It also has an oil portrait by him - a version of one in pastel - of the astronomer Sir William Herschel (BHC2764), whom he knew well, and a chalk head study of the 5th Astronomer Royal, Nevil Maskelyne (ZBA4305), as well as a number of other examples. Russell came from Guildford, which is not far from the Pierreponts' Farley Hill estate at Bramley, and we are grateful to Neil Jeffares for pointing out that he was related to the Shurlock family of Bramley, which might be how he was introduced to them. In 1804, three years after this initial commission, he did a double portrait of the Pierreponts' first two children, Anne (b. 1802) and William (b.1803), exhibited at the Royal Academy in 1805.

Both this portrait and its pair, of Mrs Pierrepont, are in their original frames. Russell's standard printed sheets on the proper care of pastels, which are easily damaged, were also still present on the original frame backings until 2006, but then removed for better preservation. Both this picture and its pair of the sitter's wife entered the Museum in 1946 from the possession of Mrs Janet Eyre, a great-great-grandaughter of the Pierreponts through their daughter Anne (Mrs Uniacke). The present one was purchased at that time: that of Mrs Pierrepont was initially accepted on loan in deference to Mrs Eyre's wish that they stay together, and purchased in 1967 from her residual estate. See the other, PAJ2906, for further family details.