The ground staff and crew yesterday at Basel did an exemplary job, I thought. If BA could manage this on every flight, I think everyone would be happy. The priority line was policed, Bronze was called only after the Club/Gold/Silver line had fully emptied, and people not entitled to be using those lines were turned away. Someone else before the jet bridge was putting yellow tags on the bags for people who had not boarded through the priority line, but didn't bother those who did.
On board, one crew member was very actively helping people put wheeled bags in the overhead and making sure all yellow-tagged bags went under the seat, even though the flight was lightly loaded.
The crew was still very much working out the kinks with BoB, but this very young looking group (BSL is Mixed Fleet, I think?) was otherwise fantastic managing boarding and bags.