Five airports with more than 2 million pax. Perhaps NCL?
Ryanair have happily abandoned the place to the more up market locos and the flag carriers of KLM / AF, Lufty, BA and EK. Ryanair have recently cut the number of flights to DUB to the point that it is proving difficult to actually get there from North East England now.
Look at NCL route map and you will see whole chunks of Europe unserved. There is a very definite gap in the market. The region is crying out for decent links to Germany, Eastern Europe and northern Italy. The people who study demographics seem to have a very blinkered view of the northern end of England and I am certain once they realise that not everyone keeps coal in the bath, races whippets and wants two weeks in Palma, then you could justify a base serving proper cities.
There is obviously no love lost between NCL and Ryanair, perhaps EI could rekindle some Irish romance?