| Honorific-Prefix: | The Right Honourable |
| The Lord Trefgarne | |
| Office1: | Minister of State for Trade |
| Primeminister1: | Margaret Thatcher |
| Term Start1: | 25 July 1989 |
| Term End1: | 23 July 1990 |
| Predecessor1: | Alan Clark |
| Successor1: | Tim Sainsbury |
| Office2: | Minister of State for Defence Procurement |
| Primeminister2: | Margaret Thatcher |
| Term Start2: | 21 May 1986 |
| Term End2: | 24 July 1989 |
| Predecessor2: | Norman Lamont |
| Successor2: | Alan Clark |
| Office3: | Minister of State for Defence Support |
| Primeminister3: | Margaret Thatcher |
| Term Start3: | 2 September 1985 |
| Term End3: | 21 May 1986 |
| Predecessor3: | office created |
| Successor3: | office abolished |
| Office4: | Parliamentary Under-Secretary of State for Armed Forces |
| Primeminister4: | Margaret Thatcher |
| Term Start4: | 14 June 1983 |
| Term End4: | 1 September 1985 |
| Predecessor4: | Jerry Wiggin |
| Successor4: | Roger Freeman |
| Office5: | Parliamentary Under-Secretary of State for Health and Social Security |
| Primeminister5: | Margaret Thatcher |
| Term Start5: | 6 April 1982 |
| Term End5: | 14 June 1983 |
| Predecessor5: | The Lord Elton |
| Successor5: | John Patten |
| Office6: | Parliamentary Under-Secretary of State for Foreign and Commonwealth Affairs |
| Primeminister6: | Margaret Thatcher |
| Term Start6: | 14 September 1981 |
| Term End6: | 6 April 1982 |
| Predecessor6: | Richard Luce |
| Successor6: | Malcolm Rifkind |
| Office7: | Parliamentary Under-Secretary of State for Trade |
| Primeminister7: | Margaret Thatcher |
| Term Start7: | 5 January 1981 |
| Term End7: | 15 September 1981 |
| Predecessor7: | Norman Tebbit |
| Successor7: | Iain Sproat |
| Office8: | Lord-in-waiting Government Whip |
| Primeminister8: | Margaret Thatcher |
| Term Start8: | 9 May 1979 |
| Term End8: | 5 January 1981 |
| Predecessor8: | The Lord Wallace of Coslany |
| Successor8: | The Lord Skelmersdale |
| Office9: | Member of the House of Lords |
| Status9: | Lord Temporal |
| Term Label9: | as a hereditary peer |
| Term Start9: | 29 June 1962 |
| Term End9: | 11 November 1999 |
| Predecessor9: | The 1st Baron Trefgarne |
| Successor9: | Seat abolished |
| Term Label10: | as an elected hereditary peer |
| Term Start10: | 11 November 1999 |
| Term End10: | present |
| Predecessor10: | Seat established |
| Birth Date: | 31 March 1941 |
| Party: | Conservative |
| Education: | Haileybury |
| Alma Mater: | Princeton University |
David Garro Trefgarne, 2nd Baron Trefgarne, (born 31 March 1941), is a British Conservative politician. He is currently the longest-serving member of the House of Lords.
The son of George Trefgarne, 1st Baron Trefgarne, Trefgarne succeeded his father as 2nd Baron Trefgarne in 1960 at the age of 19, having attended Haileybury and Imperial Service College. He took his seat in the House of Lords on his 21st birthday in 1962. In contrast to his father, who was a Liberal and later Labour politician, he chose to sit on the Conservative benches.
Trefgarne was an opposition Whip from 1977 to 1979 and then served in the Conservative administration of Margaret Thatcher as a Government Whip from 1979 to 1981 and as Parliamentary Under-Secretary of State at the Department of Trade in 1981, at the Foreign and Commonwealth Office from 1981 to 1982, at the Department of Health and Social Security from 1982 to 1983 and at the Ministry of Defence from 1983 to 1985. The latter year he was promoted to Minister of State for Defence Support, a post he held until 1986, and then served as Minister of State for Defence Procurement from 1986 to 1989 and as a Minister of State at the Department of Trade and Industry from 1989 to 1990. In 1989 he was admitted to the Privy Council.
He was president of the Institution of Incorporated Engineers when they merged with the Institution of Electrical Engineers in 2006.
Lord Trefgarne is still a member of the House of Lords as one of the ninety hereditary peers elected by their colleagues to remain after the passing of the House of Lords Act of 1999. According to the Electoral Reform Society, he has since blocked further reform of the Lords, tabling 'wrecking' amendments to a draft Bill to abolish by-elections for hereditary peers, proposed by Lord Grocott in 2018.[1]
He became the longest-serving member of the House of Lords on 26 April 2021 after the retirement of Lord Denham.[2]