Wow!Now we are learning that the Manhattan project and the atomic bomb was actually a British project at aberdeenshire somewhere and not at New Mexico. Thankfully Churchill was well aware of the true power relationship between the UK and the USA.
Actually, the UK was pivotal in getting the US to see the potential of nuclear technology from a warfare perspective, sent key scientists to it and they had their own nuclear program to boot. However, as per the (very interesting, although I think it sells the US a little short - supplying anything on Newfoundland in the face of US subs would be tough, and it was very nice of Japan in the hypothetical timeline to hit the US while it was down but leave the Brits alone) hypothetical from
@levithan123 , it would probably have bankrupted the empire to build it (not something the Brits were averse to doing, just look at their financial behaviour in WW1, although without the US to borrow from it may have been harder to pull off). I'm also not convinced that the UK would regularly strategic bomb somewhere like New York, let alone drop an atomic bomb on it.
However, and it's a huge however, just contemplating war between the US and UK in this time period, and even more contemplating 'total war' of the 'someone doesn't surrender until they have an A-bomb dropped on them, or is mostly occupied' is kinda crazy in the first place, so given that's the starting point, a hypothetical where the UK basically bankrupts themselves to build an A-bomb isn't really that crazy, in context

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