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Thanks for the link, that was a really interesting video and a bit of an eye opener for me.
The VT radio proximity fuse was produced in a wide variety of Mks through the war, starting with the MK 32 for the US 5 inch gun. Here's an image of the Mk 53 fuse of 1944 vintage:
http://upload.wikimedia.org/wikipedia/commons/b/b7/MK53_fuze.jpg
The British and the US had been working on ruggedising vacuum tubes for a radio proximity fuse from 1939 and 1940, respectively. The US devoted far more resources into it and had a workable fuse in the form of the Mk 32 by early 1942. Work on a photo-electric fuse was abandoned when the solution to the VT fuse was found.
The US developed the VT fuse through the National Defense Research Committee, specifically Section T of Division A. The US spent more than 1 billion on the research and development and purchase of VT fuses during WW2 and bought more than 22 million fuses.
The technical challenges were immense. Not only did they need to shock harden the tubes, they had to design new types of circuitry, a new type of battery, new filament types ect.
There's a pretty thorough history here http://www.history.navy.mil/faqs/faq96-1.htm
How would it work against a Mosquito, were the metal was mostly the engines, propellers, engine mounts and landing gear, none of which should be overly charged for any reason.