Is Plymouth in Wales?
As JSCL has indicated, since PLH was transformed, by Bill Bryce (RIP), from a three grass runway'd field in to a one and a half skid pan'd airfield it has been developed (only) to serve a home based carrier with just the occasional visitor.
An airport that only has half or, at best, two thirds of a runway is never going to make it in to the premier division, it's done well to survive as long as it has but it's closure has got diddly squat to do with APD.