[johndallman]

Originally Posted by Tomsdad

I'm still interested in how Britain gets the bomb though, and perhaps more importantly how quickly it can manufacture them.

Originally Posted by RogerBW

Well, as Michele said back in post #13, the trick is affording it. There are plenty of scientists and engineers who can have the necessary insights, but this is an expensive project and the UK has many other things to pay for.

Historically, the British did think of it independently. Quite a lot of people did: the paper describing the discovery of fission was openly published in January 1939. Within a year, there had been over a hundred follow-up papers. Germany and Japan were the first to start military projects, in April '39, but they didn't get anywhere. FDR reviewed Einstein's letter on October 11th. Igor Kurchatov informed his government some time the same year, and the British had their first go that year too, but stalled out.

Frisch and Peierls, German emigres in the UK who were technically enemy aliens and thus not allowed to work on military projects had a go on their own initiative early in 1940, found an easy way to calculate an approximate critical mass, and realised the job was doable. The British project was called "Tube Alloys" but most of its people ended up at Los Alamos.

Merging the projects just made sense historically: the US had far more industrial capacity and money, and was not exposed to bombing.

Originally Posted by Tomsdad

Not forgetting you also need a delivering platform a technology that also requires a significant development* and practice, it's just in OTL we were already doing that to drop conventional bombs of course.

*the B-29 bomber project cost more than the Manhattan project! Not that the B-29 was the only 4 prop heavy bomber of course but once you get away from the B-29 other options have disadvantages.

The Lancaster was thoroughly capable of dropping a atomic bomb. In fact, that was exploited by the Manhattan Project when the USAAF took against the idea of supplying B-29s. Pointing out that the British would doubtless happy to supply Lancasters changed the USAAF's mind swiftly.

The Lancaster doesn't have the same range capability as the B29, but that just means you have to launch from Okinawa rather than the Mariana Islands. The bomb shackle that was used in the B-29 for the atomic bombings was from the Lancaster, and had been developed for the Tallboy and Grand Slam bombs, the latter of which was far heavier than the WWII nukes.