Some say, erroneously, that his tutor was an uncle named Uchtryd who made him Archdeacon of Llandeilo or Llandaff when he became Bishop of the latter in around 1140.A variety of obscure medieval records give only glimpses of the man's real life.
George's, in the person of Walter the Provost, who was also Archdeacon of the city.
But there are also hints that he had access to at least one other work unknown to us today.
His 'King Tenvantius of Britain,' for example, was otherwise unknown to historians until archaeologists began to uncover Iron Age coins struck for a tribal leader in Hertfordshire named Tasciovantus.
Some people consider the several copies of a Welsh version of Geoffrey known as the 'Brut y Brenhinedd' to be his original 'ancient book'.
However, the 'Chronicle of Saint Brieuc' makes reference to several of Geoffrey's characters apparently from a source called the 'Ystoria Britannica'.