In between ministering to the needs of his parishioners, Canon Doble pursued a lifelong study of
sub-Roman Celtic Britain and
Brittany, in which he gained a European-wide reputation. He was especially interested in the
medieval vitae or 'lives', and additional legends, related to the early Christian holy men and women (or '
saints') of Cornwall,
Wales and of
Brittany. The fruit of his research was published between 1923 and 1945 in a collection of forty-eight illustrated booklets known as the "Cornish Saints" series. The later issues (from 1928) include historical commentaries by
Charles Henderson. The standalone booklets were attractive and were evidently a success with the public. In the 1930s Doble revised some of the older booklets and issued a second edition, this time with additional material by Henderson. Until Orme's
Saints of Cornwall was published in 2000, they were the most thorough, scholarly and reliable works available on the subject. At least eleven of them were translated into French, as very often the Cornish saint was also venerated in Brittany. A collected edition of the "Cornish Saints" series was edited by
Donald Attwater and appeared in 6 volumes published by the Dean and Chapter of Truro, 1960–1970. These include all the material by Doble himself, but unfortunately omit the illustrations and the essential Henderson material. The booklets include summaries of the content or translations of the most significant of the primary sources - usually saints' lives. D. Simon Evans states in his introductory essay to Doble's
Lives of the Welsh saints: It is hardly necessary to dwell here on the value and significance of these
lives. We may regard them as religious romances or novels, and as is generally agreed, they were written to enhance the cause of the church or
parochia, whose freedom and independence was not infrequently threatened at this time. In no sense are they 'historical'; indeed they have more to offer the student of social anthropology and primitive religion. Much of what they contain is pure imagination, mingled and blended with myth, folklore and legend. But, as Doble reminds us, 'Legend is history, in the sense that the legends and traditions of a people are part of its history.' Doble also collected Cornish folklore and folksong, some of which found its way into his booklets. In 1928 he was made a Bard of the
Cornish Gorseth, taking the
Bardic name Gwas Gwendron ('Servant of Gwendron') and received the Jenner medal of the
Royal Institution of Cornwall. He was responsible for the first performance of the Cornish miracle play
Beunans Meriasek since the Reformation in June 1924 (in English translation). There have since been many acclaimed productions, including those in the original
Cornish language. Doble's research also led to the revival of the
Hal-an-Tow event at the annual
Helston Flora Day. ==Death==