Press interview with Sversky

There can be no immediate invasion of England, because while Germany has complete mastery of the air over Scandinavia, she does not have it over England by a long shot. Defensively Britain is greatly superior. Her Spitfire, which I flew last summer, is a superior 'plane to any which the Germans have in great number. Therefore, no invasion of England is possible until that superiority of the air over England is achieved.

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.

Sversky comments on air superiority over the channel

I remain convinced that there will be no such invasion - unless Germany possess a huge secret armada of new types of fighting aircraft about which the outside world had as yet no inkling.

The effective invasion of the British Isles is impossible as long as its defenders remain mastery of the skies over the island and over the English Channel. The transporting and landing of large numbers of troops are unthinkable without the shield of a solid ceiling of air protection.