Neil,
The F Mk. II were bakelite, and replaced the aluminium Mk.I probably because aluminium was badly needed elsewhere. Even the D Mk V originally had a cast aluminium case, later replaced by sheet steel. I would expect the aluminium ones to have been replaced on the production lines around 1940. They were both pre-war designs, and the F Mk II was still in use in the Sixties. The D Mk.V was used at least for the duration, and possibly beyond.
Hope this helps to make up the picture.
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George Cross Island
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28-03-07, 21:04
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