Aer Lingus could do well on a daily rotation on the Gatwick route?
Don't get me wrong but is a very small airport, serving a small region, and with BFS an hour or so down the road, its maybe reached its potential. Its a bit like Carisle or somewhere.
If you live there and there is one flight a day to London, for the sake of a car journey you can have 4 flights a day, on a particular route.
Maybe if BHD didn't get a runway extension or it was delayed indefinately, Londonderry could be an alternative for FR to launch continental serves(depending on the length of the runway up there).