[jcrawfordor]

I'm referring to the Tizard mission exactly, in which Cockcroft brought a magnetron to the US for show and tell. Nuclear weapons were less of an emphasis than radar (and jet engines, also a UK-led development) at that point in time.

[aidenn0]

Wasn't the hardened valves for use in fuses also an important part of the Tizard mission?

[jcrawfordor]

Yes! I will draw a slightly roundabout connection here to my pet topics, the British shared a number of fuze concepts as part of the Tizard mission and designs based in large part on the British concepts were developed and tested at the New Mexico Proving Grounds, part of what would later become Kirtland Air Force Base. Much of this work was directed by physicist E. J. Workman, president of the New Mexico School of Mines.

I could probably rewrite the above sentence to improve it, but I focused on the magnetron because it was seen to be of special significance at the time (directly addressed issues that US efforts at e.g. MIT Radiation Laboratory were struggling with) and that there's an interesting story surrounding the couriering of the "most secret" magnetron to the US (it was briefly lost). These were the early days of "classified" as a concept and consistent techniques around safeguarding classified matter hadn't been developed, so the magnetron plays an interesting role there as well (along with documents on a number of topics, but I believe the magnetron was the only "physical artifact" brought by the Tizard mission).