Benians was born in Goudhurst, Kent in 1880. His father was the headmaster of Bethany School in Goudhurst, and it was here that Benians received his schooling. He was admitted to St John's in 1899 and became a Fellow in 1906. Benians was appointed Lecturer in History in 1912, became a Tutor in 1918, and Senior Tutor in 1926. In the same year he was made University Lecturer in History, specialising in the history of the British colonies and dependencies, and the United States of America. He was Master of St John's from 1933 until his death in 1952, and served as Vice-Chancellor of the University 1939-41.
Benians was married and had one son and two daughters.
Obituary in The Eagle: Vol 55, Easter Term 1952, p. 4
Accessible online at: https://documents.joh.cam.ac.uk/public/Eagle/Eagle%20Volumes/1950s/1952/Eagle_1952_Easter.pdf