[2] Patrick Henry Dean was born in Berlin, Germany, to Henry Roy Dean, (1879–1961), a professor of Pathology at the University of Cambridge, and his wife, Irene Wilson (1875–1959), the daughter of Charles Arthur Wilson.

After education at Cambridge, he was called to the Bar by Lincoln's Inn, and he attempted to secure a career at the Bar in London, but was unsuccessful, and as a result he joined the Civil Service.

In that capacity, Dean served as a legal adviser at the Yalta Conference in February 1945, dealing with the repatriation of prisoners, and at the Potsdam Conference, in July and August 1945.

[3] He also served as an adviser during the postwar Nuremberg trials of German war criminals and to the British Control Commission in occupied Germany.

[4] He helped to promote greater mutual understanding between the two governments, but faced a president who had a negative attitude to foreign diplomats.