Offler was born in Hereford, Herefordshire[1] on 3 February 1913; his father Horace was the general manager of King's Acre Nurseries in the city.
He then spent a year studying the theology Tripos; placing in the first class in 1934, he won the Lightfoot Scholarship and was elected to a research studentship at Emmanuel; under C. W. Previté-Orton's supervision, he worked on the reign of the Holy Roman Emperor Louis IV (the Bavarian) and visited Germany and France to study archival sources.
[6] The project published editions of Ockham's texts under the title Opera Politica;[3] the first volume had been completed by Sikes in 1940.
Bennett had carried out a revision of his and Sike's earlier work on volume two, but left Offler to complete this after 1958; the edition came out in 1963.
[5] A compilation of his writings was edited by A. J. Piper and A. I. Doyle and published as North of the Tees: Studies in Medieval British History (Aldershot: Variorum, 1996).