Centrfix,
No, I'm not saying that - only that the leisure market for all 3 is not good enough to increase and/or start a route. Even if it were, a B737 would not be the aircraft to do so with, it is too big.
CWL may be the only one with potential, albeit very limited. Main problem is that it is against Bristol and that does have a market that is served.
ABZ is NOT a leisure destination for all but a very few. Yes, the oil market is booming but that is very fixed on the times it needs flights for and it will never be like it was back in the '80s again.
BHX - it is quicker to drive!
GH