Pym, Baron of Sandy in the county of Bedfordshire, was a Tory member of parliament from 1961 to 1987. His father also served in parliament.

Pym served as an opposition whip from 1964 and was Edward Heath's Government Chief Whip from 1970 to 1973 before becoming secretary of state for Northern Ireland. Margaret Thatcher named him defense secretary from 1979 to 1981 and foreign secretary from 1982 to 1983.