Exeter is mentioned a bit and probably is a better comparing with than Bristol. I think the fact that it has less airline's and routes maybe shows that it's making it's money on other parts of the business like the Executive jet side and I believe that they own a business park nearby? Not too mention the former Flybe mro operation and I'm told that they have high out of hours charging which I don't believe CWL has. The non passenger side of the business is what CWL has been building up with the arrival of Global trek and taking over of St Athan. It'll be interesting to see how those operations effect the airports profitability in the future.
As for selling the airport in the future I don't think any WG government could risk it without some sort of golden share and a private owner is no guarantee that WG money won't still end up in the business as any canny owner would surely try and use WG money rather than their own.