Claim: Margaret Thatcher was a prime minister.
Evidence: Margaret Hilda Thatcher , Baroness Thatcher , -LRB- ; 13 October 1925 -- 8 April 2013 -RRB- was a British stateswoman , who served as Prime Minister of the United Kingdom from 1979 to 1990 and as Leader of the Conservative Party from 1975 to 1990.