NWI-EXT is a clever one.
BE cut a deal (five years?) with Regional & City Airports Ltd. to serve AGP and ALC from both NWI and EXT. A crew and a/c based in EXT can fly EXT-AGP-NWI-EXT in the AM, change crew and then do EXT-NWI-AGP-EXT in the PM. No night stops, no need for a crew base in Norwich, and the bonus is that in between the reasonably resilient sunshine routes is a loss-leading (from £19.99 one way) domestic route that'd make no sense as a daily standalone route.