I would imagine that these routes are struggling for bookings as they have such horrific arrival times at the destinations.
The inbounds are a bit better though, and you can now book one-way PMI-BHX for 7500 avios and £9.70 in Club Europe, or £17.30 for FLR-BHX, both of which are great value if arriving in BHX works for you.
The FLR flight arrives at 18:35, which leaves plenty of time to hop on a train from Birmingham International to Euston.