I have this British MKII, it looks like it use to be in all black paint but due to bad care most of it has chipped off. while trying to figure out the make and date which was heavily painted on I uncovered two small sticker like icons. It seems that there is written "PAID" and "A". I have tried to research the meaning of this but unfortunately I have found nothing close, the closest I got is a WW2 civil duty respirator with the same kind of golden border around the wording. Any help would be much appreciated. Thanks in advance.