In comparing SEN v LGW, it is worth bearing in mind that LGW is just over half the train journey time from Victoria, compared to SEN from Liv. St. LGW also has direct services to London Bridge & St P's, together with connections throughout much of the south east.
SEN is going to take pax mainly from STN, and it is going to serve the local market, so it is no surprise to see Easy in and BE out.
Who is going to operate CAX, I just can't see the point in flying to somewhere 1hr away from London compared to a direct train to Euston in just over 3 hrs. CAX is not NCL - much smaller population, and where's the big business? The Glasgow train line goes straight through, and it also serves the leisure demand for the Lake District.