A large collection of papers consisting of:
- Articles and essays (some for Eisteddfod competitions) on various topics such as poetry, maritime history, politics and individuals such as R. Silyn Roberts, Hedd Wyn and Ann Griffiths. Includes thesis by David Thomas entitled A study of a rural maritime community in the 19th century, with special reference to the relation between agriculture and shipping (University of Liverpool, 1928). Also, there are a few works by others, namely, J. Glyn Davies, William Morgan Richards of Portmadoc, T. Jones Pierce, Ffion Mai Thomas and J.D. Richards of Trawsfynydd.
- Lectures and talks for radio and television, 1934-1959, written solely by David Thomas, or by him in conjunction with others. They cover a variety of subjects and also consist of a few lectures prepared for the Workers Educational Association.
- Original manuscripts, transcripts of historical sources and research notes collected by David Thomas. Maritime history seems to feature strongly once again e.g. manuscripts relating to Caernarvonshire ships and shipping dating from 1864-1902 such as schedule of shares of vessels held and account book of the schooner G.W. Jones of Porthmadog. Extracts from Custom House registers in the ports of Beaumaris, Caernarfon and Pwllheli; transcripts of Beaumaris Custom House letters, 1714-1786 which contain a wealth of information regarding trade and shipping along the North Wales coast; transcripts of manuscripts and printed material relating to the Porth Dinllaen versus Holyhead harbour and railway controversy, the history of Lleyn (with particular reference to Nefyn and Edern). Also, newspaper cuttings, 1925-1926 relating to shipping and maritime affairs. Transcripts of census schedules from originals cover the parishes of Edern, Tudweiliog, Ceidio, and Nefyn mainly.
- Poetry by David Thomas and others, including R. Silyn Roberts, Islwyn, T. Gwynn Jones, Harri Gwyn. Includes a collection of socialist poems.
- Papers relating to political and social activities, in particular, to the activities of the labour party in Caernarfonshire. These include letters from H.G.Wells and Keir Hardie.
- The papers of David Thomas in his capacity as editor of Lleufer, which include scripts and correspondence with contributors.
- Personal and general correspondence from such individuals as D.J. Williams, George M. Ll. Davies and T. Gwynn Jones to name a few.
- Amongst the miscellaneous papers there are such items as the magazine and minute book of the Myllin Literary and Debating Society, 1889-1900, a directory of Tal-y-sarn, Caernarfonshire and a draft report of the enquiry committee on the present position of the Bangor and District Co-operative Society, 1923.