In 1924, Vaughan went to live at Tenby where he wrote his best known work of Welsh interest, viz. The South Wales Squires (1926); he had previously written a national eisteddfod essay on ‘The Welsh Jacobites’ (published in Cymm. Trans.; 1920) and a study of Thomas Johnes of Hafod and his private press (Cymm. Trans., two articles, 1911-12, 1919-20; DWB, 441-2); he was also a contributor to West Wales Historical Records, the Journal of the Welsh Bibliographical Society, Western Mail, Welsh Outlook, and some of the better known English Reviews.

Vaughan deserves to be commemorated also for his long years of devoted service (1916-48) to the National Library of Wales, both as member or chairman of some committees, and for his gifts to that institution. He gave to the Library the Oriental manuscripts collected in India by his great-grandfather, Benjamin Millingchamp (DWB, 633); on Millingchamp and the MSS. see his ‘Life and Letters of the Venerable Benjamin Millingchamp’ (now N.L.W. MSS. 13915-6) and H. Ethé, N.L.W. Catalogue of Oriental Manuscripts (1916). He was an authority on bookplates, helping to catalogue the Sir Evan Davies Jones collection and cataloguing for the National Library (1938) the Aneurin Williams collection. During his sojourn in Italy he had collected a large number of Italian books, some of them rare works; this Italian collection is now in the National Library. Just before he d. he wrote (not for publication) ‘Memoirs of a Literary Bloke’ (now N.L.W. MS. 14341) and ‘Notes on the Life of Dorothy, Viscountess Lisburne’ (N.L.W. MS. 14647), a member of a family with which he claimed kinship. He d. 31 July 1948 at Tenby.