Thomas was the eldest son of Edmund Crouchback and Blanche of Artois, Queen Dowager of Navarre and niece of King Louis IX of France.

This was due to the marriage contract the two families had agreed; upon the death of his father-in-law, Thomas would hold these earldoms in his own right, not, as would be expected, in right of his wife.

On reaching full age he became hereditary sheriff of Lancashire, but spent most of the next ten years fighting for Edward I in Scotland, leaving the shrievalty in the care of deputies.

He attempted to govern for the next four years, but was unable to keep order or prevent the Scots from raiding and retaking territory in the North.

Upon his death, his titles and estates were forfeited, and the Scots, whom Lancaster gained aid from in his rebellion, mainly to weaken the English in their war, seized the opportunity to take his inheritance in the Great Raid of 1322.

[1] On 23 March 1822, Thomas's remains were discovered in a large stone coffin buried in a field in the parish of Ferry Fryston.

[6] In 1942 it was reported by E. J. Rudsdale that some of Thomas's bones had been found in a box at Paskell's auctioneers in Colchester, Essex, having been removed from Pontefract Castle in 1885.

Inherited from his father, Thomas bore the arms of the kingdom, differenced by a label France of three points (that is to say azure three fleur-de-lys or, each).