Gwenallt 's first fields of research were the lives of the saints and rhetoric in bardic schools at the end of the middle ages (see Yr Areithiau Pros , 1934 ), and though he published studies such as Y Ficer Prichard a ‘Canwyll y Cymry’ ( 1946 ), Blodeugerdd o'r Ddeunawfed Ganrif ( 1936 , 1947 ), he is best known as a literary historian of the 19th c. In addition to numerous articles on individual poets he published Detholiad o ryddiaith Gymraeg R.J. Derfel ( 1945 ), Bywyd a Gwaith Islwyn ( 1948 ), Y Storm: dwy gerdd gan Islwyn ( 1954 ). Nevertheless, his greatest contribution was as a poet and writer . He was among the first members of Yr Academi Gymraeg and the first ed. of its periodical Taliesin to 1964 (vol.9). His father had been his first teacher and he served his apprenticeship in local eisteddfodau and at college. His awdl ‘ Y Mynach ’ won the chair at the Swansea national eisteddfod ( 1926 ) but his awdl ‘ Y Sant ’, though adjudged the best at the Treorchy national eisteddfod ( 1928 ), was not awarded the chair. He won the chair with his awdl ‘ Breuddwyd y Bardd ’ at the Bangor national eisteddfod ( 1931 ). The poems, sonnets and longer narrative poems in his collections of verse, Ysgubau'r Awen ( 1939 ), Cnoi Cil ( 1942 ), Eples ( 1951 ), Gwreiddiau ( 1959 ), Y Coed ( 1969 ) are more personal and express the poet 's deeply held convictions, his attitude to life and a complex personality. Running through his work are the threads of his attachment to Wales and her culture, and his meditation on the nature of evil which threatens the civilization of which the poet and his people are part. As his writing developed and his response to materialistic, industrial society and to the crisis in Wales grew more intense, his style became ever more uncompromising and rougher. His two novels, Plasau'r Brenin ( 1934 ) and Ffwrneisiau ( 1982 ), which draw on his experiences in prison and as a lad in the Swansea valley are not as successful as his poetry.

Gwenallt was committed and serious in everything which he undertook. He was one of the early members of Plaid Cymru , he was politically minded and keenly interested in current affairs (the result of sustained thinking about his personal experience in an industrial environment) and he experienced a difficult but triumphant spiritual pilgrimage as he revealed in his essay in Credaf (ed. J.E. Meredith , 1943 ).