Because I pointed the reason why a B.B. was needed in the channel to counter any possible big ships supporting an invasion.
A pre-dread’ maybe old, is still quite a handle for cruisers.
Lets look at this claim with a quick side by side
First off here's a brief listing of the home fleet during 1940
so let put the
HMS Devonshire (Heavy Cruiser) up against the
SMS Scleswig-Holstien (pre Dred BB)
Full load for not operating on long patrol: 10Kt vs 13Kt
Length and width: the S-H is wider, shorter and has a deeper draft than the Cruiser Devonshire
Speed: 32Kn vs 19kn (the Devonshire has also just under 5x the installed power* of the S-H)
Main guns: 4x twin 8" vs. 2 x twin 11"
Torpedoes: 2x Quad 21" tubes vs. none
Armour: OK let's just say a pre dred BB S-H has a lot more than the Devonshire!
OK so the S-H has a clear advantage in armour and really that's about it
In terms of main guns the range is comparable, I agree in abstract the Devonshire is less able to withstand a hit from the S-H's 11", than the S-H is from the D's 8" but even then it's not like 40mm of deck armour is going to stand up to plunging fire from 8" guns, but the Devonshire is harder to hit, and the S-H is less able to hit due to the technology it had. The Devonshire has double** the volume of fire. (The surface area and dimensions of the S-H also makes plunging fire a bit easier as well)
But's it not going to be gun dual unless the Devonshire fancies a challenge, its going to be 35kn Mk VII torpedoes at a slow and relatively un-manoeuvrable target. But what about that nice thick torpedo belt, yeah it's nice and thick, pity it doesn't help much against WW2 torpedo tactics of varying run depth and/or breaking a ship's back. This class of German pre-Dreds had issues with torpedoes in WW1.
However the biggest difference is that while there's only a 21 years split in commissioning dates, that was a very full 21 years in terms of naval development. The S-H turned up to WW1 outdated, and the D was developed with the lessons of WW1 learn't. Hell the S-H was outdated at it's date of commision!
Now going back to the first link How many Heavy Cruisers were about? (oh and god help it if a battlecruiser turns up) even light cruisers although having 6" guns will have the same torpedo tubes
*this one might not be as sexy as how many big guns and how thick was the armour, but actually when your operating and positioning against each other on the sea that's a big thing!
**actually it's more, according to Navweaps the German 11" has rof of
2 rounds per min, while the British 8" was more like
3-4 rounds per min (I also guess the train rates were slower on the german gun etc)