Sarah A. Oppenheim-Barnes, Baroness Oppenheim-Barnes, PC (née Viner; born 26 July 1928) is a British Conservative politician.
Born in Dublin in 1928, and raised and educated in Sheffield where her father worked as a diamond cutter, Viner was educated at Lowther College and worked as a social worker in London before entering politics.
In the 1970 general election she defeated John Diamond to represent the constituency of Gloucester; Diamond was the only cabinet minister to lose his seat at that election. Some found her previous occupation to be somewhat appropriate — she had worked as a diamond cutter. She continued as Member of Parliament for Gloucester until 1987 and was Minister of State for Consumer Affairs in the Department of Trade between 1979 and 1982.
Oppenheim-Barnes was created a life peer, as Baroness Oppenheim-Barnes of Gloucester in the County of Gloucestershire, on 9 February 1989. Her son Phillip Oppenheim was formerly Conservative MP for Amber Valley. Between 1983 and 1987 mother and son served simultaneously in the House of Commons.