In the dark days of the invasion scare of 1940 and 1941, British ingenuity was released to provide weapons to halt any invasion. Britain had amassed massive stores of petrol, in expectation of having to supply the BEF in France. These stores were made available to the Petroleum Warfare Department to develop uses of petrol as a weapon.
One of the weapons was the Flame Fougasse.
The name comes from the late medieval weapon using a barrel of gunpowder to make a one shot giant shotgun.
These are to be markers for Operation Seal Lion games (so are not accurate representations).