We disagree and that's what makes this such a wonderful world to be in.
The fact is, you've not been to Southend (clearly) as my times allow a wait for the train and neither have you been to Carlisle as even in bad traffic from the station to the airport is around a 16 minute drive.
Eitherway, it clearly saves times to fly, you would rather take the train. Go for it and enjoy the views …
I've made my point and stand by what I know to be accurate, if you agree or not is your prerogative!