[6] In the tumultuous years that followed Dupplin Moor, Thomas's grandmother, Lady Christina Bruce, held the seat of the earls of Mar, Kildrummy Castle.
When David was eventually released in 1357, Thomas was one of the seven lords “from whom three were to be selected as hostages” until the king's ransom was paid.
In addition, the English king agreed to pay Thomas £600 sterling yearly if he lost his lands in Scotland.
[13] Earl Thomas was in both England and France frequently in his life, as John Mackintosh has laid out in his book Historic Earls and Earldoms of Scotland: In March, 1359, he had a passport through England for himself and thirty persons in his retinue, and three merchants; while in August, 1359, he had a safe conduct for himself and one hundred horsemen in his train.
In July, 1365, he had a licence to send eight horsemen to Newcastle-on-Tyne with one hundred and twenty oxen, which he had sold to merchants in that city.
Thomas died childless, some say in 1374,[19] others in 1377,[20] the confusion arising from the fact that his brother-in-law was already claiming the title Earl of Mar in 1374.