Just a few toughs on the GSM situation.
1. MME has a larger catchment area than NCL
2. GSM have an existing relationship with Peel
3. GSM will have had experience with operations into MME by the time a transatlantic service starts from the North East
4. GSM may fly via LPL from MME
5. IT will be cheaper to fly from MME than NCL
6. MME's terminal is less crowded so you can get through quicker, also the new terminal will improve on this as well.
Yes NCL is the more established airport in the minds of the public but this is the type of route MME needs to redress this balance.