Hubert Rutherford Purnell was born in Oxford, England, on 13 August 1882. He began his library career as a junior assistant at Oxford University's Bodleian Library and also in Oxford worked at Queen's College Library before becoming librarian in charge of the Central Reference and Lending Libraries at Croydon (England). He was appointed Principal Librarian of the Public Library, Museum and Art Gallery of South Australia and emigrated in 1913. He commenced employment at the Library on 31 March 1913.
Purnell enlisted on 20 April 1916. He trained as a Bombardier and embarked from Melbourne on HMAT A15 Port Sydney on 9 November 1917. Purnell served in France with the 27th Reinforcement of the Field Artillery Brigade and then the Educational Unit of the AIF and achieved the rank of Lieutenant. At the end of the War he was granted a leave of absence from the Army to complete an educational tour of libraries in England before returning to Australia. Purnell married Ella Glanvill in Lewisham, Kent in early 1918. He returned to Australia per the Borda 16 December 1919 and returned to his position at the Library.
In August 1928 Purnell was appointed treasurer of the newly formed Australian Library Association, and was inaugural secretary of the Library Association of South Australia from 1929. He was actively involved in the establishment of the Friends of the Public Library Society in Adelaide. His notable achievements as Principal Librarian include the establishment of a research department and creation of the country lending service.
Purnell died on 12 March 1944 at his home at Unley Park, Adelaide.