Following the work of Otto Frisch and Rudolf Peierls at the University Of Birmingham the Air Ministry had established the highly secret MAUD Committee to examine the practicality of building an ‘Atomic’ bomb. On the 15th July 1941 the scientists on the committee produced their final report:
We should like to emphasize at the beginning of this report that we entered the project with more skepticism than belief, though we felt it was a matter which had to be investigated.
As we proceeded we became more and more convinced that release of atomic energy on a large scale is possible and that conditions can be chosen which would make it a very powerful weapon of war.
We have now reached the conclusion that it will be possible to make an effective uranium bomb which, containing some 25 lb of active material, would be equivalent as regards destructive effect to 1,800 tons of T.N.T. and would also release large quantities of radioactive substance, which would make places near to where the bomb exploded dangerous to human life for a long period.
The bomb would be composed of an active constituent (referred to in what follows as -U) present to the extent of about a part in 140 in ordinary Uranium. Owing to the very small difference in properties (other than explosive) between this substance and the rest of the Uranium, its extraction is a matter of great difficulty and a plant to produce 2-4 lb (1 kg) per day (or 3 bombs per month) is estimated to cost approximately 95,000,000 pounds, of which sum a considerable proportion would be spent on engineering, requiring labour of the same highly skilled character as is needed for making turbines.
In spite of this very large expenditure we consider that the destructive effect, both material and moral, is so great that every effort should be made to produce bombs of this kind.
One of the key recommendations of the Committee was that their research should be shared with scientists in the United States. This was the crucial step towards the establishment of the Manhattan project.