Claim: Margaret Thatcher was the most senior politician within the Conservative Party in the UK in 1975.
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.
The Leader of the Conservative Party is the most senior politician within the Conservative Party in the United Kingdom.