People power will decide but apart from the novelty of flying there seems alot of faffing around particularly when there are better alternatives from London. 4 flights a week at different random times of the day verses 2 trains an hour which would do the complete journey quicker than by air. Might come down to price in the end as the plane is often cheaper than the train with some train fares dearer than flying the Atlantic.
Train, check-in, wait in lounge, flight, minibus Vs Train. I would have to live close to Southend to make the plane the preferred method of travel. It will be interesting to see if the route becomes a summer only route as the Lake District is dead in the winter compared to the summer crowds.