[1] He was born in Killeek, County Dublin, son of John Mitchell.
[3] In 1372 he and Roger Hawkenshaw,[4] the Escheator of Ireland, appeared as expert witnesses at a lawsuit in Kilkenny before the Court of King's Bench (Ireland), where Philip Overy claimed possession of certain lands allegedly left to him by Thomas le Botiller.
[7] In the same year he and John FitzRery, the new Escheator of Ireland, were ordered to collect the King's debts.
[8] He held office briefly as an ordinary Baron of the Exchequer in 1376,[3] and as Chief Baron of the Irish Exchequer in 1376-7, and was then transferred to the Court of Common Pleas (Ireland) as its Chief Justice.
His predecessor Robert Preston, 1st Baron Gormanston, was removed from office at his own request, "unless the King or Privy Council of Ireland should order otherwise";[2] Preston apparently retired voluntarily due to advancing age.