He travelled to Sicily as a child in the entourage of Robert of Selby about the year 1130.
Thomas was a kaid, or magister, of the royal Diwan throughout the reign of Roger II, whose favour he certainly had.
His name appears in many official documents and it was probably he who drafted the foundation charter of the Cappella Palatina.
The Greek transcription of his name and title was μαστρο Θωμα του Βρουνου.
Upon the succession of William I in 1154, Thomas was removed from office (possibly by the Emir Maio of Bari) and returned to England.