Aer Lingus have become more and more competitive in recent times, in 2007 they added DUB-LGW and were seen as the underdog on the route but they stuck with it and next month to take advantage of BA's withdrawal, they'll increase frequency to match Ryanair's.
Aer Lingus still compete with easyjet on 4 routes from BFS and the arrival of Aer Lingus meant Jet2 had to pull off the BFS-BCN route. All you have to do to see how competitive they plan to be at LGW is look on the front page of their website and check out the fares!
At DUB, Aer Lingus returned to NCL and made it a year round service at a time when Ryanair is reducing flights to NCL. Aer Lingus also keep their twice daily BCN service while Ryanair reduces frequency to GRO and in ORK, BmiBaby pull BHX and Ryanair pull EMA while Aer Lingus reaffirm their commitment to BHX from ORK.
While not all of their ventures have been huge successes, it does prove that Aer Lingus is willing to try new things and compete directly with the likes of Ryanair and easyjet!