The History of the Kings of Britain (Penguin Classics)
Very little is known of Geoffrey of Monmouth.  He seems to have lived for a time in Oxford and in 1151 he became Bishop Elect of St Asaph, North Wales.  He was ordained at Westminster in 1152.  According to the Welsh Chronicles he died in 1155.      Lewis Thorpe was Professor of French at Nottingham University from 1958 to 1977.  He has published many books and articles on Arthur, both on the French and English traditions.  He died in 1977.