Sir David Brand ( 1 August 1912 â `` 15 April 1979 ) was the 19th Premier of Western Australia from 2 April 1959 to 3 March 1971 . Sir David Brand KCMG ( 1 August 1912 -- 15 April 1979 ) was the 19th and longest serving Premier of Western Australia and a Member of the Legislative Assembly from 1945 to 1975 .