BE would be a good fit for the ANR route, the baseline seems to be 30-odd pax per flight 3x daily paying decent fares. It’s easy to see potential for that to be grown a little, and much more potential for additional lower-yielding leisure traffic to add to the mix.
Antwerp is a pretty good short-break destination that seems to underperform with British travellers, perhaps because it’s a little under the radar by virtue of it being too small to handle EZY/FR etc and another hour or so from Brussels if you come by train. Rotterdam isn’t too far but that isn’t particularly well connected directly by air from the UK either.