Surely these are more likely to be the worn out, slow, old MkII machines which were retired from Europe and shipped out east in an attempt to stop the japanese expansion? I've read somewhere (Churchill maybe??) that a number of those were never unpacked because the jap advance was so quick. Its likely that these were buried in 1942 - NOT 1945 and somehow I expect the key consideration at the time was simply to hide them, not to preserve them.