sxflyer:
As for Northern Europe, there is no route to Hamburg from STN or LCY so that could be a good shout, other previous guesses of mine were Kristiansand and Paderborn.
FlyNonstop managed only to scrape together 8,467 passengers the around six months they flew KRS-LCY before they went bust. My advice to Stobart would be: Don't even think about it.
The three larger Norwegian airports could be something for them and all three have flights only to Gatwick and Heathrow and with that no coverage to the north and east of London. The three airports are:
OSL (Oslo Airport, Gardermoen)
1,014,434 passengers to London in 2013 = 37% of all passengers between Norway and the UK
The passenger numbers grew with 8% from 2012.
BGO (Bergen Airport, Flesland)
308,809 passengers to London in 2013 = 11% of all passengers between Norway and the UK
The passenger numbers grew with 52% from 2012.
SVG (Stavanger Airport, Sola)
284,450 passengers to London in 2013 = 10% of all passengers between Norway and the UK
The passenger numbers grew with 24% from 2012.
As a reference: one daily return trip for a 72 seat ATR72-600 equals to 52,560 seats to fill in a year and 5 weekly flights generate 37,543 seats to fill in a year.