The man in the portrait is William Shipley (baptized on June 2, 1715 – December 28, 1803).
He was born in Maidstone, Kent, the son of Jonathan Shipley (d. 1749, originally of Walbrook, London) and Martha (née Davies).
He was well known as a drawing master, social reformer and inventor who, in 1754, founded an arts society in London that became The Royal Society of Arts, or Royal Society for the encouragement of Arts, Manufactures & Commerce, (RSA).
On November 23, 1767, William Shipley married Elizabeth Miller, and retired to Maidstone about 1768. The couple’s first child was born in 1769 but died after two months. In 1771, The second child, Elizabeth was born. Shipley, under the auspices of Lord Romney, founded a local institution, “The Kentish Society for the Promotion of Useful Knowledge”, along the lines of the Society of Arts. In 1783 the society was instrumental in improving the sanitation of Maidstone gaol, and so preventing the “gaol fever”, which had ravaged the prison population of the country.
Shipley was an inventor in his own right. He came up with ideas on how to provide inexpensive fuel for the poor, a floating light in order to save those lost in the sea (for which he received an award), a way to establish new species of fish in ponds around England, and perhaps strangest of all, a method of lining your shoes with tinfoil in order to keep them dry. Shipley died in Maidstone, aged 89, on 28 December 1803. A monument was erected to his memory in the north-west corner of churchyard of All Saints Church, Maidstone. Richard Cosway painted an oil portrait of Shipley, and there is also a portrait, drawn and engraved by William Hincks, in the National Portrait Gallery (London). There is a mezzotint by John Faber Junior of a painting by Shipley of a man blowing a lighted torch.
More can be read about William Shipley here