Game keeper's alarm guns are quiet a rarity. They were spiked into the ground in an upright position and a trip wire taken from then across a footpath or bridleway. If the trip wire was triggered the drop weight fired a blank cartridge. This example is of interest because it is marked in the following manner. A crown, with the initials BP below it. A diamond around the number 12, below which is a small c. A pair of crossed swords with the letters S and B and the number 2. The word BLANK.