Driving times etc
Everyone seems to be making too much of the journey times. For example, from here in Medway the journey times to Manston Gatwick and Stansted are very similar, whilst Heathrow is a pain and Luton a terrible pain. I have flown from Heathrow and Luton simply because there were flights going where I wanted when I wanted and at the price I wanted. If Manston or Southend or even Lydd had what people wanted they would be quite willing to undertake the extra journey. I have met people at Gatwick who have driven up from Gloucestershire or Devon or even flown down from Scotland just to get the flights they want so I cant see any problems there.
Also in my experience the presence of a railway station is of no consequence in most cases because it is very difficult to get a train for an early morning flight or to get home again after an evening arrival. Most passengers have to go via one of the central London stations which is the Achilles heel of the journey.