Willesee joined the Australian Labor Party when he was 21 and was elected as a senator for Western Australia in 1950 at the age of 33, taking office as the Senate's youngest member. He worked with Whitlam to reform the Labor Party prior to the 1972 election. According to Kim Beazley he was a "... key assistant to Gough Whitlam as he set about the task of restructuring the Labor Party ... and made an intelligent, brilliant rabble fit for government." Following the 1972 election, Willesee was appointed as Special Minister of State, Vice-President of the Executive Council, Minister assisting the Prime Minister and Minister assisting the Minister for Foreign Affairs in the second Whitlam Ministry. As Special Minister of State he endorsed the establishment of a computerised library information system to connect national, state and university libraries, which has continued to evolve. Whitlam relinquished the position of Minister for Foreign Affairs to him on 30 November 1973 and in this period he had the major responsibility of implementing the Whitlam government's, ambitious new foreign policy directions, which included improving relations with Asia. For Willesee, this meant Australia taking a more pragmatic approach to international affairs; in a speech to the Australian Institute of International Affairs in June 1974 he declared: "the first duty of Government is to recognise and comprehend the world as it actually is, not as we might conceive or wish it to be. That is a cardinal principle of the way this Government has approached foreign policy. Australia, if it is to serve national interests in an effective manner, can no longer afford to impose on international events interpretations at variance with the facts." This approach translated into action in various ways, on 26 February 1973, Willesee led the push to recognise the Democratic Republic of Vietnam, and directed the establishment of the Australian Embassy in Hanoi in July 1973. A new Embassy in East Berlin was also established in East Germany in March 1975 following recognition of the GDR in 1973, as well as a new Embassy in Pyongyang, North Korea on 30 April 1975. Willesee was opposed to Indonesia's invasion of East Timor and is quoted as having said in 1975: He did not stand for re-election at the 1975 double dissolution election.
Death
Willesee died in Joondalup Hospital, Joondalup, two weeks after a heart attack, survived by his wife Gwen, and their six children, Colleen, Mike, Terry, Geraldine, Don junior and Peter. Through Terry, he was the biological paternal grandfather of author and cyclist Janet Shaw. He was the last surviving member of the 1950-1955 Senate. At his death, the Prime Minister said: According to the leader of the opposition at the time,
