A Welsh Classical Dictionary contains biographical and historical articles on Welsh and Brythonic people up to about the year A.D. 1000 who appear in early Welsh historical manuscripts. It also includes some articles on place-names and mythical and legendary characters.
P.C. Bartrum was born in Hampstead, north London in 1907. He was educated at Clifton College, and to Queen's College, Oxford, where he studied Relativity. After training as a surveyor at St John's College, Cambridge he worked as a meteorologist until his retirement in 1955.
It is said that his interest in genealogy was generated by his desire ‘to put things in order’, and he began by researching his family tree. Although he had no links with Wales, he learnt to read Welsh and developed a lifelong interest in the history and genealogy of the Welsh nobility of the Middle Ages, becoming 'the foremost scholar of medieval Welsh genealogy'. In 1974 he published an 8 volume series entitled Welsh Genealogies AD 300-1400, and a further 18 volumes entitled Welsh Genealogies AD1400-1500 were published in 1983. He continued to add and correct these publications, and presented his amended manuscripts to the Welsh Department at Aberystwyth University, who digitised the collection. P.C. Bartrum died aged 100, in 2008.
A Welsh Classical Dictionary, people in History and Legend up to about A.D. 1000, was published by the National Library of Wales in 1993. In his introduction P.C. Bartrum refers to the volume as ‘a series of notes arranged alphabetically under personal names and a few place-names’ which ‘are the result of many years of working in the field of early Welsh history, legend and fiction, and are to some extent biased towards subjects which were of personal interest’ to him, with ‘a leaning towards genealogy and to the development of historical ideas’. He has attempted to ‘give the essential outlines of legends and fictions, generally telling the stories without comment, interpretation or speculation.’