Willem Drees Sr. was a Dutch politician of the defunct Social Democratic Workers' Party and later co-founder of the Labour Party and historian who served as Prime Minister of the Netherlands from 7 August 1948 to 22 December 1958.
Drees studied Accounting at the Amsterdam Public Trade School obtaining an Bachelor of Accountancy degree and worked as a bank teller for the Twentsche Bank from July 1903 to July 1906 as a stenographer for Parliament from January 1907 until August 1919. Drees was elected as a Member of the House of Representatives after the election of 1933, taking office on 9 May 1933 serving as a frontbencher and spokesperson for Social Affairs. After Party Leader and Parliamentary leader Willem Albarda was appointed as Minister of Water Management in the Cabinet De Geer II Drees was selected as his successor on 10 August 1939. Shortly after the German Invasion Party Leader Albarda announced he was stepping down and Drees was anonymously selected as his successor as Leader on 14 May 1940.