Numerous collections of folk songs and hymn tunes accumulated by J. Lloyd Williams before and during his period as Editor of the Journal of the Welsh Folk-Song Society, including material which he himself had recorded and items submitted to him by others. Indexes, lists, related notes and press cuttings are also included.

Lecture notes relating to Welsh folk songs and folk tunes, including two series delivered at Bangor, 1934 and 1935, Coedpoeth, 1937, Llangefni, 1940, and a lecture entitled 'Neilltuolion Alawon Gwerin Cymru', undated but apparently delivered at Cardiff.