James Michael Leathes Prior, Baron Prior, PC, is a British politician, and was the Tory MP for Lowestoft and Waveney.
He was first elected to Parliament in 1959, and was Minister of Agriculture, Fisheries and Food from 1970-1972, then Leader of the House of Commons and Lord President of the Council until 1974. Under Margaret Thatcher he was Secretary of State for Employment from 1979 to 1982, then Secretary of State for Northern Ireland until 1984. This transfer was widely seen as a move by Margaret Thatcher to isolate Prior, who disagreed with her on a number of economic issues. The post of Secretary of State for Northern Ireland was for a time seen as a 'dumping ground' to marginalise ministers. He retired from Parliament in 1987 and was later created Lord Prior.
He is Vice President and was Chairman of the Rural Housing Trust.
| Preceded by: Cledwyn Hughes | Minister of Agriculture, Fisheries and Food 1970-1972 | Followed by: Joseph Godber |
| Preceded by: Leonard Robert Carr | Lord President of the Council 1972-1974 | Followed by: Edward Short |
| Preceded by: Albert Booth | Secretary of State for Employment 1979-1981 | Followed by: Norman Tebbit |
| Preceded by: Humphrey Atkins | Secretary of State for Northern Ireland 1981-1984 | Followed by: Douglas Hurd |