He was born in Redruth on 29 October 1900, the son of Alfred Hamilton Jenkin, and his wife, Amy Louisa Keep.
He attended University College, Oxford, where in 1919 he became a friend of the famous author, C.S.
Jenkin was a founder bard of the Gorseth Kernow in 1928, taking the bardic name Lef Stenoryon ('Voice of the Tinners').
He was elected President of the Royal Institution of Cornwall for the years 1958, 1959 and was vice-president in 1977.
In 1954 he was elected a Fellow of the Society of Antiquaries and was awarded his honorary degree of Doctor of Letters by the University of Exeter in 1978.