Yes, that Thomas of Lancaster
He lost his head at Pontefract so what was he doing on sale in Colchester?
This Kathryn Warner post gives a lot of detail about Thomas Earl of Lancaster’s life, rebellion and execution six days after the Battle of Boroughbridge. Here we explained the circumstances in which John Ashdown-Hill is seeking his remains, to solve the York/ Beaufort Y-chromosome mystery.
Incidentally, the other Thomas of Lancaster you may encounter in a search engine was Henry V’s brother and Duke of Clarence but died at the siege of Bauge, a few months before his King and exactly 99 years after his namesake.