OK the Firth of Solway isn't golden beaches, ice cream parlours and kiss-me-quick hats, but it is part of the coastline of Britain, and it's about 20 miles from Carlisle Airport.
But the problem with coastal areas is that they don't have a full 360 degrees of catchment area, and that's my point in using the word 'coastal'.
Newcastle is more coastal than Carlisle, and it does ok. The whole argument about coastal airports struggling is a load of rubbish, it's all about the size of the catchment area, not the degrees of catchment. Blackpool has a population of 140,000, 2 major airports on it's doorstep, and a contract with a low-cost airline that left them with next to no profit. That's why it struggled, not because it was built next to the coast!