WATABENCH
I believe Viking operates MD 83 aircraft and the Friday flight to CWL from HER routes via EXT inbound each week. Not sure of the tour operator (s).
As for taking one step back etc, it seems there is a bit of consolidation about at present at a lot of airports. For example our local airport at BRS has lost several routes this coming winter, the latest to go seemingly the Flybe daily TLS which originally was shown to be operating through the winter.
Maybe the easyJet competition on the route has taken its toll.