Let's not forget that the Communist Party of that time was totally controlled by Moscow, and that members were expected to tow the Party line--it would not have been unreasonable for a commanding officer to be concerned that Jimmy Miller, or any other Communist organizer, might be carrying out orders from Stalin. It certainly happened.

It also happened that Communist organizers were recruited and used by Allied Intelligence to avert strikes in industries involved in defense , and to generally keep labor in line. Also to keep tabs on other Communists.

MacColl's seeming desertion in wartime, with no apparent consequences, is unusual, in the very least. The fact that he seems to have disappeared, then re-appeared with a new name that suggested a past very different than his true background adds even more zest to the tale.

If he'd been an American entertainer, our British counterparts would likely be outraged by any suggestion that it was improper to ask questions about the distant past--and they'd be right--