[1] He succeeded Thomas Le Boteller, who died on military service in France in 1420.
In April 1422 the Council appointed him Lord Lieutenant of Ireland: he held that office until the following October.
[1] In 1417 he witnessed an important charter of King Henry V of England, guaranteeing the liberties of the citizens of Dublin.
[3] Despite his high offices, he was to some extent under the control of the Archbishop of Armagh, in particular as regards his Order's substantial lands in County Louth.
In both cases, Fitz Thomas seems to have felt obliged to comply with the Archbishop's orders.