One thing I will add to this is that those of us up at LBA would love some longhaul, just as you in Bristol would, but if someone op BRS - LBA I would be just as delighted as its far more sustainable!
BRS does have some weekly long haul charter routes in summer: TUI to Cancun and Sanford, with Punta Cana joining next summer. TUI also operates year-round to Sal, Cape Verde with a second Cape Verde route, Boa Vista, starting next year. What BRS lacks is long haul scheduled routes.
Some years ago I wondered why easyJet didn't begin a BRS-LBA route. At that time their BRS-NCL was operating up to 4 x daily and carried over 260,000 passengers annually. In recent years the route has reduced in frequency and annual passenger numbers have slumped to 165,000. The train is doubtless the main culprit with an hourly service between Bristol and Newcastle via Leeds. A BRS-LBA with easyJet looks unlikely now. bmi regional might be thought to have been/be an option but they've shown no public interest.
I would therefore dispute the fact that MT would make less money out of CWL if the same theory is applied. Orlando was a huge market pre 2010, when at it's peak there was a weekly 767 and A330, along with a high density 747 during the peak summer months, over 1000 seats a week, and then the FCA flights from BRS at the time on top of that.
I have no doubt whatever that such flights would be full from CWL. I remember that one month in August 10-15 years ago 10,000 passengers used Cardiff-Florida. As you will know better than most, getting an acceptable yields for such flights is the important thing. I was always surprised that when Thomson and First Choice merged ten years ago the CWL summer transatlantic programme was axed in favour of BRS. Up until then CWL usually had the lion's share of such routes with TOM and Airtours as well as chartered carriers for smaller tour companies. First Choice concentrated more on BRS than on CWL.
You could also argue then that giving Wales control of APD won't make a difference to BRS anyway so why not devolve it? If CWL is cheaper even with APD and not making a difference to BRS growing is it going to make a difference with APD devolved?
The professionals at CWL want APD devolution. The professionals at BRS don't. This seems a pretty strong indication that APD would benefit CWL whilst detracting from BRS.
I'm not a believer in artificially manipulating the jobs market by taxation and other government benefits. What often happens is that few new jobs are created but existing jobs move from one area to another as companies take advantage of a more agreeable fiscal climate.
If I was looking to open a new airline base on Severnside an APD-free CWL would be a very attractive prospect. On short haul I would take nearly £2,000 more on every outbound flight from CWL with 150-seater size aircraft, even if I charged the same fares as I would have done from BRS. Long haul would give me about £15,000 per flight on a 200-seater aircraft. This is based on full flights although I might use a 180-seater and expect to average at least 150 per flight.
Let's look at Qatar. Let's assume they begin modestly and average 150 per outbound flight. That's nearly £12,000 per flight, around £80,000 per week, about £320,000 a month and nudging £4 million a year. In an APD-free Wales they could pocket that every year whilst still charging a similar range of fares as they do at BHX and would have done at BRS had they gone there.
Imagine how much more TUI would make with their 20-weeks' season flights to Cancun, Sanford and Punta Cana, and weekly flights to Sal and Boa Vista. They'd be averaging probably 260-290 passengers on most of these flights so the APD take would be high - £2-3 million in a year.
Both Qatar and TUI would appreciate the flexibility of not having to hand over APD to the Treasury. They could trouser all of it or reduce fares by a little or a lot to attract more punters, depending on circumstances.