Churchil compares the Skagerrak to the Channel

In the Skegerrak, because of distance, we could give no air support to our surface ships, and consequently, lying as we did close to the enemy's main air power in Norwegian waters, we were compelled to use only our submarines. We could not enforce a decisive blockade or interruption of the enemy's surface vessels. Our vessels took a heavy toll but could not prevent the invasion.
But in the Channel and in the North Sea, on the other hand, our forces, aided by submarines, will operate with close and effective air assistance … In the fighting over Dunkirk, which was a sort of no-man's land, we undoubtedly gained a local mastery of the air and inflicted on the German air force losses on the scale of three or four to one. Anyone looking at the photographs of the re-embarkation, showing the masses of troops assembled on the beaches, affording an ideal target for hours at a time, must realise that this embarkation would not have been possible unless the enemy had resigned all hope of air superiority at this point.