I think I'd noticed the passenger fees at Bristol had increased. I'm sure they used to be about GBP16, but the since 1st March 2013 they seem to be closer to GBP20. (SN show it as GBP17.90 and KL as about GBP20.87).
That has an effect on the final price charged to passengers, but I suspect there's very wide latitude for negotiation on those fees. I would imagine FR didn't get the 'negotiation outcome' they wanted.
I think the BM flight to VRN on Saturday is a charter, so whilst they will have got paid for operating the flight, they weren't selling the tickets.