http://www.marconicalling.com/museum...-i=64-s=6.html

"In Britain the Royal Navy had for some time been aware of the
importance of ultra-short wave radio for inter-ship communication and
early in the Second World War had contracted with Birmingham University
to conduct research into transmitting and receiving valves functioning
at 10 centimetres. Research conducted by two young scientists assigned
to the project, John Randall and Harry Boot, resulted in the creation of
the cavity magnetron, which was small enough to be held in one hand, yet
could produce 400 watts of power at the required 10 centimetre
wavelength, over 100 times more than the most powerful valve then in
existence, the klystron.

In August 1940, at the height of the Battle of Britain, the cavity
magnetron was taken to the USA by a small party of scientists and
service officers, led by Tizard. The Americans were so impressed that
production of the British cavity magnetron began within weeks."

I'd say the US knows a gift when they see it?

Cheers MC