Born in Durham, North Carolina, son of a merchant Thomas Ellis Allen and Harriet Moore, he attended Duke University—then known as Trinity College—graduating in 1924[1] and from Harvard University in 1929.

He joined the Foreign Service in 1930 working first as vice consul in Kingston, Jamaica and later in Shanghai, China; Patras, Greece; and Cairo, Egypt.

During this period he worked on preventing a Soviet-Iran oil agreement and led to the Iranian prime minister Ahmad Qavam dropping communist cabinet members.

He also helped build ties with Shah Mohammed Reza Pahlavi, playing weekly tennis matches with the monarch.

[9] Allen appeared as himself, while serving as the Director of the Foreign Service Institute, on the February 6, 1967 episode of the game show To Tell the Truth.