As I was trying to book these flights for later on in the year, I messaged Flybe.
Their response:
Unfortunately this is down to availability on this selected route.
Sorry for the inconvenience.
At which point I pointed out they simply cannot be damn near fully booked on every flight of the year from April onwards, and asked if the flights would be cancelled.
Their respone:
Not that I am aware of Adam. Thank you for the congratulations on our Cardiff base I am sorry that I am unable to advise you further
Closure by stealth it is then. It seems Flybe at SEN is becoming 1960s British Rail.....
Adam