I do not have enough knowledge about the music transmitted to radio receivers in Norway during WW2, but I found some info:
On 9.April 1940 Norway was invaded by Germany and the media was allegedly put under control by pro German people (Nasjonal Samling). Them or the Germans, I don't know for sure.
I am reading that allied forces transmitted propaganda which led to the banning of the use of radio autumn 1941 (wikipedia) and the confiscation of half a million radios. Apparantly, only the people of NS Nasjonal Samling was allowed to own a radio. I don't know if it was also illegal to own a radio up to 1941.
Some people hid away their radios, covertly listening in on BBC transmitting from London.
NRK P1 = possibly the only national radio channel in Norway at that time.
Don't know what NRK P1 did after 1941, if they were twiddling thumbs or whatnot.