I'm wondering about how this would alter the careers of The Twins.
- Would they have sunk Renown in their encounter with her off Norway in 1940?
- Would they have sunk Glorious, Acasta and Ardent faster? IIRC Scharnhorst was torpedoed in the action and Gneisenau was torpedoed by a submarine in an operation intended to cover the damaged Scharnhorst's passage back to Germany. If they had been less heavily damaged they might have had time to fit in another Atlantic sortie before conducting the one of OTL.
- If Brest was better protected could they have been made operational in time to come out and support Bismarck and Prinz Eugen?
- It looks as if Bismarck would have made St Nazaire ITTL and then be transferred to Brest to join the Twins and Prinz Eugen. The RAF would be throwing everything it had at them, but the improved AA defences would make them pay a heavy price and while the RAF was bombing Brest it wasn't bombing Germany. If the Channel Dash is as OTL they all reach Germany safely apart from mine damage.
- If the improved effectiveness of Germany's AA defences prevents the bombing of Gneisenau in 1942 then the Germans have a fleet in being consisting of Bismarck, Tirpitz and both Twins at least until the end of 1943, which was when Scharnhorst was sunk IOTL. But ITTL the Arctic convoys might not be attempted at all had Germany possessed a fleet that strong.