What the hell are you talking about LTNman ... have you been spending too much time in the phone kiosk again?
Terminating at a London terminal? ... So all of LHR,STN & SEN's punters travel by a train that terminates at a London terminal?
Just at random I've just run a check on SEN to Wimbledon, Wimbledon is south and west of London is it not?
SEN airport (rail station) to Wimbledon rail station = 1hr 35mins and without a terminus at a London terminal.
Whilst ... LTN airport to Wimbledon rail station = 1hr 40mins with a terminus London/St Pancras.
Here's an interesting map that shall provide a connection between the world's busiest airport and your beloved SEN:
