Oslo has been around for some time before, it's too think to warrant a 738. But would a q400 be a good niche 4 times per week for Flybe... Purely speculative on my party but I'm guessing there probably is core level of demand, hence, ability to charge realistic fares...?
Braathens (Now part of SAS) operated daily except Saturday,service mainly operated by 737-500, but occasionally larger 737s to Bergen via Stavanger.
A separate daily, except Saturday service was operated to Oslo, also using B737-500 aircraft. These services were competitively priced in competition with the Ferry services to Norway.
Edit:
Service for 95/96 Winter season showing departure times was:
(From Newcastle Airport Winter Timetable 95/96)
Bergen (via SVG) 12345 -- BU574 10.25 B737
Bergen (via SVG) ----- - 7 BU578 19.45 B737
Oslo 12345 - - BU568 18.05 B737
Oslo ----- - 7 BU564 12.15 B737
Apparently Ferry services ended due to competition from Low Cost Flights (although by this time it was Ryanair, who operated briefly)
Braathens were a full service airline, with very reasonable fares. A lot of traffic came from Norway to Newcastle for shopping. I remember a Tax Refund desk being available for Norwegians returning home.
I guess this service / services may be a success for Norwegian or possibly EasyJet if marketed correctly.