What if the Washington naval treaty of 1922 had allowed the British Royal Navy to keep its prior two power standard and build the Nelson class battleships and complete the rest of the admiral class (HMS Hood’s class) rather than have the same amount of capital ships as the American Navy?
As other's have written, it's not going to happen, but I'll play along.
For context the two power standard meant the royal naval would have more capital ships than the next to largest naval powers after the UK combined, in the context of this scenario, the USA and Japan.
The OTL tonnage quotas were:
525,000 tons British Empire
525,000 tons United States
315,000 tons Japan
175,000 tons France
175,000 tons Italy
ITTL the tonnage quotas would be:
840,000 tons British Empire (525,000 tons plus 315,000 tons).
525,000 tons United States
315,000 tons Japan
175,000 tons France
175,000 tons Italy
The OTL Treaty classed the 3 Colorado class the USA ship was allowed to retain as Post Jutland Ships and the Japanese Nagato & Mutsu were also classed as Post Jutland Ships. The only Post Jutland Ship possessed by the British Empire was Hood. Therefore, the Treaty allowed it to build 70,000 tons of capital ships by 1930 (which was used to build Nelson & Rodney).
The TTL Treaty would allow the British Empire to build 140,000 tons of capital ships by 1930 which it would have used to build four Nelson class battleships. That would have given the British Empire five Post Jutland Ships to match the five possessed by Japan & the USA (Nagato, Mutsu & the 3 Colorados).
Assuming the Americans, Italians, French and Japanese accept this agreement, what happens next?
I'll get back to you on that one.
How would a bigger Royal Navy affect ww2?
And this one.
What ships that the Royal Navy scrapped would be retained?
As already related the UK was allowed to have 20 capital ships displacing 558,950 tons when Nelson & Rodney were completed IOTL. However, ITTL the British Empire's allowed at least 827,170 tons in 1930 to match the 525,850 tons the USA was allowed and the 301,320 tons was allowed. (Or if it was done strictly by the tonnage quotas 840,000 tons). Which is a shortfall of 268,220 tons.
IOTL Thunderer, King George V, Ajax & Centurion (which were replaced by Nelson & Rodney) came to 91,500 tons. They'll be retained ITTL, but that still leaves nearly 177,000 tons to find. Keeping the other three superdreadnoughts (Orion, Monarch and Conqueror) would add 67,500 tons which means about 110,000 tons left to find. Lion & Princess Royal add another 52,500 tons so the remaining 55,000-odd tons would have to be the older 12in gunned battleships or battle cruisers.
That would make a total of 34 or 35 capital ships in 1930 consisting of 4 Nelson class, 5 Queen Elisabeth class, 5 Revenge class, 4 Iron Duke class, 3 King George V class, 4 Orion class, Hood, Repulse, Renown, Tiger, Princess Royal, Lion and three or four 12in gunned dreadnoughts. The WNT would allow these to be replaced by twenty-four 35,000 ton capital ships (total 840,000 tons) to be laid down 1931-39 and completed 1934-42.
Except that all other things being equal the First London Naval Treaty would extend the battleship building holiday to the end of 1936 and the British Commonwealth would reduce its existing capital ship force to 24 ships with immediate effect. My guess is that the 24 ships would be the 4 Nelson class, 5 Queen Elisabeth class, 5 Revenge class, 4 Iron Duke class, Hood, Repulse, Renown, Tiger, Princess Royal and Lion which works out as 18 battleships and 6 battle cruisers.
Would this just mean the British empire had to spend more money on the Royal Navy to keep its ships running or would it be worth it for the Second World War?
I'll have to get back to you on that one.
How would this alter the naval strategies for the Kriegsmarine, Regia Marina and the Imperial Japanese Navy?
Don't know.
How could this alter some naval battles in the Second World War?
Don't know.