There was a time when both Braathens and Dan-Air operated NCL-BGO and NCL-FBU. Dan had a daily NCL-BGO-SVG-NCL 146 operation and a daily NCL-FBU-NCL operation with either 146 or 1-11-500. Braathens had a 737 operation on NCL-BGO and FBU, I think it was around five flights per week on each. Dan also did NCL-Gothenburg at one point. It was back in the day when the Metro Centre was new, in all fairness!
I don't recall BA Connect ever flying NCL-Oslo (happy to stand corrected) but I do remember Norwegian Air Shuttle having a short-lived go at NCL-Bergen after Braathens disappeared - I think it was with Fokker 50s as they had at the time.