Sorry to dig up this thread again, but I was just having a think about these routes and whether BA could bring them back.
I know the oil industry was a big driver for these routes, but surely they could bring them back with a more leisure orientated focus. Bergen is a great city break and a key access point for the Fjords. Leisure routes have taken off over the last few years, with BA having a strong presence in other Winter holiday destinations (Reykjavik, Turin, Innsbruck, Cologne), so it may work on low frequency.
They make Billund work, which is smaller and another secondary Scandinavian city. It’s also a shame as other European carriers all serve Bergen (even Iberia!).
Maybe when the 80/20 rule comes back and they need to keep slots warm, it will reappear.