The collection contains material collected by John Lloyd-Jones whilst compiling his work Geirfa Barddoniaeth Gynnar Gymraeg. The material takes the form of slips of vocabulary, and also slips of place-names, personal names and elements of Gaelic names. The original manuscript of the work is included, proof sheets with amendments and a notebook with references to old and medieval Welsh texts.
There are dissertations, notebooks and awdlau in the hand of John Lloyd-Jones, but most of his poetical works are photocopies of original manuscripts. The testimonials and applications for various posts date from 1909 - 1921.