But earlier posts suggests that, quite correctly, many of the passenger would be for international connections.
So if they departed CAX in the morning, arrive SEN later in the morning, fart around with a train into a London station, then on the underground to another London station, then on an under or overground train to a London airport, well they'll, by then, already have missed many of the departures that day.
Alternatively, from CAX, they could nip across to NCL and do things the simple way with a flight to AMS or LHR etc. and a minimal connection time before contiuing their journey.
Need to convince people that CAX offers an alternative to NCL and that wouldn't be achieved by services to SEN.