Why is the knight going to the shrine of St. Thomas?

The destination of all the pilgrims is the shrine of Saint Thomas à Becket (1118?-1170) in Canterbury Cathedral, in which he was entombed after he was murdered in the church on December 29, 1170. He was both a martyr and a saint. I'm not sure that the Knight has a different motive than the others to go on this "holy pilgrimage". The real reason was actually not so much the destination than the trip itself. On their way thepilgrims ate much food, consumed copious amounts of alcahol and told the best stories ever!

You can get more info on Saint Thomas à Becket at the source-link below