He was the Agassiz Professor in Chinese and Comparative Literature at University of California, Berkeley before his retirement.
[1] In 1947, Birch was discharged from the army, and he returned to England, where he studied for a BA degree in Modern Chinese at SOAS.
He received a first class degree in 1948, and then continued studying Chinese literature at SOAS as a graduate student under the supervision of Walter Simon.
He taught Chinese language and literature at SOAS until 1960, including a year's sabbatical in Hong Kong where he learnt Cantonese.
He held the post of Louis B. Agassiz Professor in Chinese and Comparative Literature at his retirement in 1990.