Before he rose to the position of Bishop of Dunkeld, he had been Master of the famous hospital at Soutra Aisle, and the tutor to King James II of Scotland.
It would therefore appear that Thomas was the natural son of Sir Robert de Lawedre, Knt., of Edrington and The Bass (died before Michaelmas 1451), the only brother of Bishop William Lauder who was a knight.
On 7 October 1444, he sent a Supplication to Rome stating that he was the "peaceful possessor without adversary" and requesting the Pope (Eugenius IV) to give him a Dispensation "to rule and govern for life the said church or House of Soltre as a simple hospital and secular benefice".
Father Thomas Lauder had also been tutor to Prince James, the future King James II of Scotland, as evidenced by a Supplication to Rome made by the King on Thomas's behalf, on 26 November 1454, asking for the Bishop to be excused from visiting all parts of his diocese because "it is mountainous and inhabited by wild Scotsmen and certain enemies".
He had been provided to the See of Dunkeld in 1452 where he exercised his functions very laboriously until the year 1476, when, being unable any longer to endure the fatigue by reason of his advanced age, he resigned the Bishopric in favour of James Livingston, the Dean.