The Inverness area does seem to be a hotbed of heresy for some reason; I'm guessing it's hardcoded into the game. I'm further guessing that this reflects the Lollards, much as the heretical element in Toulouse reflects the Albigensians.

Check out this guy:

http://www.gashe.ac.uk:443/isaar/P0243.html

who was the "Papal Inquisitor of Heretical Pravity in Scotland" What a great job title.