This also happened to us at Edi last Saturday (18/07). Flight was due to land at 23.05, though I think we ended up around 15 minutes late. It was around 1am that the bags finally appeared.

Baggage Enquires had already gone home for the night though a couple of BA staff were there trying to get hold of someone who could find out what was going on but it took a long time and quite a few people did give up and go (we were just back from 2 weeks and lots of shopping in NYC so hung on but were starting to wonder at what point we would give up and go).

We were told the reason for the delay was 'operational reasons' but when the bags did turn up they were soaking wet so it seemed as though they had been offloaded from the plane then left and forgotten about.