Air Southwest don't serve EXT?!
A service from EXT would probably work but I wouldn't try it if you didn't want to upset BE who are not starting to become the FR on a regional scale: you fly between our bases, we'll do it too until you can't afford to compete then we will drop it the same time you do - remember My Travelite?
I think a good route for ASW would be a Saturday service of NQY-BLK-JER-NQY but I am only saying that because I don't like using MAN for regional flights and want to fly ASW more often!