It's been said, many a time, and it's true that BRS and CWL have totally different catchment areas and clientel in those areas.
BRS has picked up on the market, both business and leisure, for folk all the way from Lands End up until circa Gloucester, across to Swindon and mid point to the BOH area. These folk would otherwise need to travel all the way to such airports as LHR/LGW.
CWL, on the other hand, has a sparsely populated catchment area with reletively little business travel demand, which KLM have something of a monopoly serving, and mainly holiday leisure travel for once, or twice, yearly holidays of which many will book inclusive tour package holidays and not opt for a LoCo seat only even if a LoCo is serving the destination they wish to holiday in.
Because of CWL's sparsely populated, and nature of, catchment area it's never likely to be a busy passenger airport and, as with the BA maintenance facility, might focus it's attention to making revenue from aviation related business other than passengers ..... but,:
Now they've decided to develop the former RAF St. Athan that's within spitting distance of CWL, to create an enterprise zone or whatever offering businesses financial incentives to come and develop their business at St. Athan, so what chance of CWL attracting non passenger related aviation business now?
Just as an example, in the 80's, Norman were making crop sprayers over where the CWL flying club(s) are, no chance of any business revenue like that returning because they'd opt for St. Athan instead.
Just by reading such threads as this it is apparent that South Wales hasn't been able to support one profitable licensed aerodrome so who the **** decided to develop a second licensed aerodrome and within spitting distance of the first licensed aerodrome?