The eldest surviving son of Alexander Burnett of Leys and Katherine, eldest daughter of Alexander Gordon of Lesmoir, "Thomas Burnaetus de Leyes" appears in the records of King's College, Aberdeen and Aberdeen University, as a student who matriculated in 1603. In 1604 and 1606 when he was a witness to sasines he is designed as his father's "son and heir apparent", whom he succeeded in 1619 in the feudal barony of Leys and a range of other lands and rights. He completed the work of restoring Muchalls Castle, which his father acquired in the year 1588.
