Starflyer on the LBA/Flybe thread states that the LHR flights are merely 'slot sitters'.
https://forums4airports.com/threads/217/post-243706
"The only reasons AMS, BHD and LBA were chosen as destinations for LHR were that Flybe have seven daily slots to cover at Heathrow and needed routes to do it until such time as they can achieve a sale of those slots. This route hasn't even got a short term future let alone a long term one. I'd not spend too much time discussing ifs, buts and maybes around it."
This seems to imply that Flybe were awarded these slots and are using the flights to hold onto them until such a time that they can sell them for a very nice profit.
Kevin