Thomas Pengelly, by his wife Rachel, the eldest daughter of Lieutenant-colonel Jeremy Baines. He was probably born at his father's house ‘next door to the 2 Twins in Moorefields,’ and was baptised in Moorfields on 16 May 1675. His father was an opulent London merchant, who traded to Smyrna, Aleppo, and the Indies as early as 1642, and possessed considerable property at the east-end, Finchley, and at Cheshunt in Hertfordshire. At his house at Churchgate, Cheshunt, he provided a retreat for the ex-Protector Richard Cromwell on his return to England in 1683. After his host's death, Richard Cromwell, under the disguised names of ‘Mr. Clarke’ and ‘The Gentleman,’ continued to reside at Cheshunt with Pengelly's widow and son, and he died there on 12 July 1712, in the younger Pengelly's arms. The intimacy between Richard Cromwell and the Pengelly family led to the fabrication of a scurrilous and lying report that the younger Pengelly was Richard's natural son.
Thomas in youth closely applied himself to study, and showed much aptitude for classics. In December 1692 he was admitted into the Inner Temple; was called to the bar in November 1700, and in 1710 was made a bencher of the inn. His practice grew rapidly. He was for many years counsel to Charles Seymour, ‘the Proud’ duke of Somerset, and to Sarah, duchess of Marlborough. In 1705–6 he was one of the counsel retained by Richard Cromwell in the suit instituted against his daughters to obtain possession of Hursley Manor, in which he had a life interest under the will of his son Oliver. Pengelly obtained a decision in his client's favour. He was created serjeant-at-law on 12 May 1710, was knighted on 1 May 1719, and on 24 June of the same year, on the death of Sir Thomas Powis, was appointed king's prime serjeant. In January and February 1722 as king's serjeant, with the other law officers of the crown, he had the conduct of the indictment of Christopher Layer [q. v.] and others before the committee of the House of Commons on a charge of high treason.
He was elected member of parliament for Cockermouth in Cumberland, chiefly through the interest of the Duke of Somerset and the Marquis of Wharton, in 1717 and in 1722. In May 1725 he was one of the managers of the impeachment of the Earl of Macclesfield [see Parker, Thomas, 1666?–1732], and on the tenth day of the earl's trial replied to all the legal points raised for the defence. Pengelly argued that the sale of the lucrative offices of the court of chancery—the chief offence with which the earl was charged—violated statute law, and that the prisoner had in an illegal and arbitrary manner extended the power and authority of the lord chancellor and of the court of chancery beyond their lawful and just bounds.
Pengelly's reputation as a counsel was excelled by none in his generation. He spoke simply yet convincingly, and spared himself no pains in mastering his briefs. He often placed his services gratuitously at the disposal of poor suitors. On 16 Oct. 1726 he was appointed lord chief baron of the exchequer, in succession to Sir Geoffrey Gilbert [q. v.] Besides sitting at the Guildhall and at Westminster, he presided at many provincial assizes. The qualities that had characterised his career at the bar distinguished his conduct on the bench. Few judges more signally commanded public confidence. Richard Steele, who resented a judgment which deprived him of the licence for Drury Lane Theatre, found no more powerful means of attacking him than by quibbling upon his surname—‘As “Pen” is the Welsh word for head, “Guelt” is the Dutch for money, which, taken with the English syllable “Ly,” signifies one who turns his head to lie for money.’
In 1730, while presiding at the Lent assizes at Taunton, Pengelly was attacked by gaol fever, to which he succumbed, at Blandford in Dorset, on 14 April. He was buried in the Inner Temple vault, in the Temple Church, on 29 April. A few years before his death he built the house which has long been known as ‘Pengelly’ at Cheshunt, Hertfordshire, on the site of the old mansion-house which had belonged to his father. He was unmarried.
By his will, which was written by his own hand, and dated 16 March 1727, and by two codicils, he directed 2,800l. to be applied to the discharge of poor prisoners for debt lying in the gaols of the towns in which he had presided as judge on the western circuit or in London. He bequeathed to his sole executor, John Webb, esq., of the Inner Temple, the whole of his estates in Hampshire and Hertfordshire, as well as his personal property, including his books and manuscripts. He left bequests to the Duchess of Marlborough and to the Duke of Somerset. His portrait, in his robes as lord chief baron, three-quarter length, painted by G. Worsdale, is now in the possession of Mr. F. E. Webb of 113 Maida Vale, London, the present representative of his heir. A second portrait, also in his official robes, was painted by the same artist; it was engraved by Faber. A large mass of his papers—his correspondents included the chief public men of his time—
