The No 1 Pull Switch was a small detonating device that was used to set off a larger demolition charge or a booby trap. It was designed to be attached to a trip wire and when that was pulled it released a striker that set off a percussion cap that in turn fired the charge. Today these sort of switches are most associated with the SOE (who did indeed use them extensively for resistance purposes), they were however just as likely to see service with Royal Engineers and others tasked with booby trapping items in front of an advancing enemy.
Naturally these sort of devices are quite scarce on the collectors’ market and most that are available have been dug up from wartime rubbish dumps. Despite this they can be quite complete and the example we are looking at today is in pretty good condition, considering it has most likely spent 75 years in the ground:
The following period diagram shows how the pull switch would have looked when new, as well as giving a cut away diagram showing the internal parts:
As can be seen, my example is pretty complete, the only part missing being the fuse adapter and the safety pin is rusted solid and partially broken now. The anchor bracket is still attached and free to move around:
The whole pull switch should unscrew and dissasemble. My example partially strips, but I am loathe to force the other piece off in case I damage the device:
Markings are pretty sparse, unsuprising if it was intended to see some service with resistance forces. There is just a single set of initials stamped into the brass near the safety pin:
The original manual gives a detailed description of the pull switch as well as suggestions on how to use it:
These little pull switches are a fascinating and quite unusual piece of British military equipment and a nice addition to my tiny selection of demolitions kit.