Elliott was head master of Eton College from 1933 to 1949. His had been an unlikely selection. For example, he was the first head master of Eton who was not in holy orders, and neither his preaching in chapel nor his teaching in school were as impressive as those of his charismatic predecessor, Cyril Alington. However, he was an effective headmaster who was respected by the school's governing body for his sound judgement and his administrative skill. He was known to his students as "The Emperor", because of his imposing presence and his coolness towards the majority of his pupils. Elliott made no significant change to the school, believing that the selection of good and effective teachers was the school's best way forward.
