Sir Thomas Plumer, (1753–1824), judge and politician, was born on 10 October 1753, the eldest son of Thomas Plumer (1711–1781) of Lilling Hall in the parish of Sheriff Hutton in the North Riding of Yorkshire, formerly a wine merchant in London, and his wife, Anne (d. 1795), daughter of Henry Thompson of Kirby Hall, Yorkshire. He was at Eton College from 1763 to 1771, then went to University College, Oxford. Reputed ‘one of the best scholars among the undergraduates’ (Maurice, 25), he graduated BA in 1775, MA in 1778, and BCL in 1783. In 1777 he was elected Vinerian scholar and in June 1780 became a fellow of his college.
Plumer had entered Lincoln's Inn on 6 April 1769 and while pursuing his legal studies attended Sir James Eyre on his circuits, frequently assisting him by taking down the evidence at the trials over which he presided. Called to the bar on 7 February 1778, he joined the Oxford and south Wales circuit. After eight years he felt he was ‘in the way of gaining both reputation and connexion’ (Jerdan, 3.3) and he later became one of the leaders. He was also a commissioner of bankrupts from 1781 to 1793 and king's serjeant of the duchy of Lancaster from 1785 to 1813. He practised with particular success in the court of exchequer, where he was greatly in demand in tithe cases, and became renowned for his expertise in parliamentary election disputes.
Plumer became known to a wider public from his appearance in a succession of notable state trials. The ability he showed when employed in the defence of Sir Thomas Rumbold at the bar of the House of Commons in 1783 led to his being retained, along with Edward Law (afterwards Lord Chief Justice Ellenborough) and Robert Dallas (later chief justice of the common pleas), to defend Warren Hastings. During those interminable proceedings he was made a king's counsel on 7 February 1793 and was elected a bencher of his inn in the Easter term following. His skilful performance in the Hastings trial led to his being retained in 1796 for John Reeves, charged with publishing a seditious libel, and in 1798 for James O'Coigley, Arthur O'Connor, and others charged with high treason. He subsequently appeared for the crown in the prosecutions of Joseph Wall, governor of Goree, for murder (1802) and Edward Marcus Despard for high treason (1803), and in 1806 he deployed his notable skill in cross-examination on behalf of Henry Dundas, first Viscount Melville, in his impeachment by the House of Commons, securing an acquittal on all the charges after a fifteen-day trial. In the same year he assisted John Scott, Baron Eldon, and Spencer Perceval in challenging the findings of the so-called ‘delicate investigation’ into the conduct of Caroline, princess of Wales, through their letter to the king of 2 October 1806.
On 27 August 1794 Plumer married Marianne (1775–1857), eldest daughter of John Turton of Sugnall, near Eccleshall, Staffordshire; they had five sons and two daughters. In 1811 Plumer purchased an estate at Canons, Stanmore, Middlesex.
Plumer had been appointed second justice on the north Wales circuit on 25 March 1805, a post he held until 1812, and, when William Cavendish-Bentinck, third duke of Portland, formed his administration in spring 1807, he was made solicitor-general (11 April) and knighted (15 April). At a by-election in May he was returned for Jacob Pleydell Bouverie, second earl of Radnor's borough of Downton, taking up a standing offer made after Plumer's legal efforts had ensured that Radnor's influence would prevail there, but which he had hitherto declined. Coming to the Commons rather late in life, Plumer did not shine as a debater, but he was a regular and dependable defender of the Portland administration and that of his friend Perceval which followed. He showed himself opposed to reform proposals of almost every kind, whether for ending the slave trade (1807), abolishing sinecures (1810), extending the parliamentary franchise (1810), or removing Roman Catholic disabilities (1811). This conservatism extended to law reform. In a debate on the criminal law in 1810 Plumer declared himself attached to the existing system of law and ‘extremely jealous in his views of any new theories’ and in 1813 he opposed two of Romilly's measures for the reduction of capital offences, insisting that severity was necessary for the security of the state.
On 26 April 1812 Plumer succeeded Sir Vicary Gibbs as attorney-general. He was regarded as indolent in some quarters but this may have been due to chronic ill health. After Perceval's death he had no desire to remain in politics and when an act was passed in April 1813 to alleviate delays in chancery by creating a vice-chancellor he pressed his claims so insistently that Eldon felt obliged to appoint him despite having practically promised the post to Richard Richards. He took office on 14 April and was sworn of the privy council on 20 May.
Plumer's appointment was strongly criticized, particularly by Romilly, who claimed that ‘a worse appointment … could hardly have been made’ (S. Romilly, Memoirs of the Life of Sir Samuel Romilly, 3 vols., 1840, 3.102). Romilly exaggerated Plumer's ignorance of equity and he learned quickly enough for his promotion to master of the rolls in succession to Sir William Grant on 6 January 1818 to attract no hostile comment.
The creation of a vice-chancellor did little to ease the plight of chancery litigants and Plumer's judgments were frequently and successfully taken to appeal, probably more because of the ready availability of appeals and rehearings than his shortcomings. Until he secured a Treasury grant to provide a new courtroom in Lincoln's Inn the vice-chancellor's hearings were conducted in conditions which ‘lessen[ed] the public reverence for a judge’ (Bell, 9), and, though he was praised for urbanity and politeness, inexperience made him very slow and encouraged litigants to file interlocutory motions purely for delay. His reputation also suffered from the prolixity of his judgments, which sometimes led his court to be deserted by all but the reporter and gave rise to the rhyme which circulated at the chancery bar: ‘To cause delay in Lincoln's Inn two diff'rent methods tend; his Lordship's [Eldon's] judgments ne'er begin, his Honour's [Plumer's] never end’.
Nevertheless, Campbell wrote in 1857 that Plumer's judgments had acquired a respectable reputation. The best-known, Dearle v. Hall (1823), on the priorities between competing equitable interests in pure personality, was later embodied in statute.
Plumer had extensively renovated the Rolls House and its chapel in Chancery Lane at his own expense and after struggling against illness for some months he died there on 24 March 1824, aged seventy, and was buried in the chapel on 1 April. He was a devout Anglican and firm sabbatarian, who gave generously to charity. A captain of the Bloomsbury and Inns of Court Volunteers in 1798, he served as treasurer of Lincoln's Inn in 1800, and was a trustee of the British Museum and a fellow of the Royal Society and the Society of Antiquaries.
Patrick Polden DNB