A retained Norway and the Atlantic war

If Britain and France had held Norway, how might that have changed the European war?

It could have denied Germany key resources and bases while strengthening Allied control of the northern Atlantic and Arctic routes.

Norway's iron ore, fish oils, ports, and geography connected its campaign to the wider naval war. British bombers, fighters, radar, and maritime-patrol aircraft based along the Norwegian coast could have made U-boat access to the Atlantic much harder. Forcing U-boats to remain submerged through much of the North Sea would reduce their effective range, while air-to-surface radar would make even night surfacing more hazardous. Allied control of the coast would also have changed the later Arctic convoy problem. A follow-up makes the scenario conditional on Britain having enough aircraft, trained crews, and cruisers to exploit those bases. Germany would still have held French ports in the proposed scenario and could have tried to move submarine sections there by rail for assembly and launch. Holding Norway would therefore alter the contest over Atlantic access without removing every German response. The suggestion is that holding Norway could have shortened the European war by perhaps a year or more, but the timing is explicitly uncertain.