The collection consists of letters, reports, minutes and accounts relating to Cymdeithas Alawon Gwerin Cymru (Welsh Folk-Song Society), 1922 - 1931. Also, papers of a similar nature relating to Y Gyngres Geltaidd (The Celtic Congress) which also include papers given at various meetings by notables such as Saunders Lewis, Sir Percy Watkins and E. T. John, 1924 - 1947.
There are files containing material relating to Plaid Genedlaethol Cymru, its members in Caernarfonshire and, in particular, regarding the incident known as the Fire in Lleyn in 1936 when Saunders Lewis, D. J. Williams and Lewis Valentine committed a token act of arson on building materials assembled for the construction of an RAF bombing school at Penyberth, Caernarfonshire.
There are addresses by Saunders Lewis made during his 1931 and 1942 General Election campaigns for the University of Wales seat.
Also, letters and papers relating to the establishment of the Folk School of Pant y Beiliau, 1933 - 1942. Correspondence regarding the National Playhouse of Wales in 1934. And, letters written to Mai Roberts from various correspondents, 1924 - 1964.
There are references for Mai Roberts when applying for posts, 1928 - 1941 and an address by her when standing in the Local Council Elections as the Plaid Genedlaethol Cymru candidate for Upper Llanddeiniolen, Caernarfonshire in 1967.
The papers of E. T. John consist of letters to him, copy letters written by him, and drafts of addresses and newspaper cuttings, 1910 - 1931.