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.

A small volume written in the eighteenth century lettered on the spine 'Llyvr Dos=parth a Cadwe= digaeth Cerdd Dannau, I'. The scribe was David Jones ('Dewi Fardd') of Trefriw. The contents are as follows: pp. 1-23, 'Clod Cerdd ai Dechreuad' beginning 'Fy Mryd sydd ar hyn om llafur ddwyn ar ddeall it Darllewr . . . Eithr o arfer Cerdd Theoricall y Nef, ni ymadroddwn am dano' [cf. B.M. Addit. MS 14989, ff. 82 recto-111 verso, and also D. Gwenallt Jones, 'Clod Cerdd Dafod', in Llên Cymru, I, pp. 186-7, and Gwendraeth Jones, 'Siôn Conwy III a'i Waith', in B.B.C.S., XXII, pp. 23-4 in particular]; pp. 24-30, 'Gryffydd ap Cynan Twysog Cymru a wnaeth Gyfraith ar y Gwyr wrth Gerdd, yr hon a elwir Ystatud Gryffydd ap Cynan', beginning 'Llyma y sawl y sydd rydd yddynt Glera . . .' and ending '. . . a Disgyblion, gwedi Cael graddau or blaen mewn Eisteddfodau neu Neithorau Reiol. Ac felly y Terfyna Ystatud Gryffydd ap Cynan Twysog Gwynedd, ar y Gwyr wrth Gerdd'; pp. 32-54 , 'Naw o Gyd-gordiadau sydd mewn Desgant neu Brior . . .' followed by lists of airs, etc. ('Ar y Bragod Gywair', 'Y Clyme, y Gogywair', etc.) ending with 'Llyma'r 24 mesurau Cerdd Dant' and 'Llyma y Rheolau Cerdd Dafod'; p. 55, 'Llyma Lyfr a Elwir Cadwedigaeth Cerdd Dannau' beginning 'Nid amgen, Telynnau, a Chrythau o fewn 3 Talaith Gymru . . .'; p. 59, 'Llyma fal y nodwyd wrth Ystatud Gryff: ap Cynan, Rhoddion i bob Gradd yn ei Radd, o Gerdd Dafod, a Thant', beginning 'Tair Gwyl arbennig sydd nid amgen Nadolig, Pasg, ar Sul gwyn . . .'; p. 62, a 'cywydd' by William Llun ('Cywydd i ofyn Telyn i Siencin Gwynn, o Lan=idlos'); and pp. 65-71, a list of the names of bards ('Henwau'r Beirdd'), A-R, with one or two later additions, one name on p. 66 ('Gruffdd. ap Lln. Vychan'), being probably in the autograph of Edward Williams, 'Iolo Morganwg'. There is a triad on p.54. On the fly-leaf in a later hand is written 'Dosparth Cerdd Dafod'.

A tune-book, [1880-1884], which once belonged to Ylltyr Williams, Dolgellau, containing traditional harp tunes; together with transcripts by J. Lloyd Williams and others from the Ylltyr Williams Manuscripts, [1900x1940].