Tim, I'm sure we have discussed what a B.M. is on here before, but I cannot find the thread. However, I don't think it was resolved in any case. I have come across BM numbers in several of the listings of the missing from both Chindit expeditions and in some other WO361 files at the National Archives. Some of these men did become POWs, but most were simple posted as missing or killed. Here are a couple of examples: