Thomas reorganised the cathedral chapter during his archiepiscopate, establishing a group of secular canons with individual prebends to provide the clergy with income. The cathedral chapter at York had until then lived in a group, but Thomas' reforms allowed the clergy to live in their own houses. Thomas also set up a number of officials within the cathedral chapter, including a dean, treasurer, and precentor. He increased the number of clergy in the chapter, increasing it from the three he found at York when he took office, and reorganised the episcopal and chapter's estates, giving a number of estates to the chapter. He introduced the continental system of archdeacons to the Diocese of York, dividing the diocese into territorial units and appointing an archdeacon to each. Archdeacons were responsible for aiding the bishop or archbishop with his episcopal duties, collecting revenues, and presiding over some judicial courts.