“A W” stands for ‘Ariel Weapon’ and this term was used before ‘incendiary’ was adopted. In WW2, the ARP put up these precaution signs in factories, shelters and public buildings because they thought people would get confused about what to do when encountering one of these devices.

This particular sign came from a factory, rather than a shelter. This is obvious from the wording on the sign itself. With a hole in each corner, this sign was screwed to a wall and retains excellent condition, with only minor marks on the front and rear. Something you can’t tell from the pictures is that it’s made out of sheet metal – making it flat, durable but on the heavier side, almost a kilo and considering it’s 12 x 8 inches in size it gives you some sense of feel for it.

These signs also give you an idea of the feel of things in factories during WW2. The fact these signs were posted up with precautions served as a reminder that workers were dealing with some VERY dangerous items.