[1] A colleague of David Lack during the war years, he conducted studies on insect population dynamics in Wytham Woods.
[2] Varley studied at Manchester Grammar School before joining Sidney Sussex College, Cambridge in 1929 with a scholarship.
He won the Frank Smart Prize for zoology in 1933 and became a researcher at the Entomological Field Station.
During World War II, he worked on radar installations on the coast where he was a colleague of David Lack.
In 1945, Varley became a reader in entomology at King's College, Newcastle-on-Tyne and in 1948 he was appointed Hope Professor at Oxford.