assistance of William Howard Livens. Livens was well known for his First World War invention: the "Livens Gas and Oil Bomb Projector", known more simply as the Livens Projector. The Livens Projector was a large, simple mortar that could throw a projectile containing about of explosives, incendiary oil or, most commonly, poisonous phosgene gas. The great advantage of the Livens Projector was that it was cheap; this allowed hundreds, and on occasions thousands, to be set up and then fired simultaneously catching the enemy by surprise. One of Livens' PWD demonstrations, probably first seen about mid-July at Dumpton Gap, was particularly promising. A barrel of oil was blown up on the beach; Lloyd was said to have been particularly impressed when he observed a party of high-ranking officers witnessing a test from the top of a cliff making "an instantaneous and precipitate movement to the rear". The work was dangerous; Livens and Banks were experimenting with five-gallon drums in the shingle at Hythe when a short circuit triggered several weapons. By good fortune, the battery of drums where the party was standing failed to go off. The experiments led to a particularly promising arrangement: a forty-gallon steel drum buried in an earthen bank with just the round front end exposed. At the back of the drum was an explosive which, when triggered, ruptured the drum and shot a jet of flame about wide and long. The design was reminiscent of a weapon dating from post-medieval times called a fougasse: a hollow in which was placed a barrel of gunpowder covered by rocks, the explosives to be detonated by a fuse at an opportune moment. Livens' new weapon was duly dubbed the flame fougasse. The flame fougasse was demonstrated to Clement Attlee, Maurice Hankey and General Liardet on 20 July 1940. Experiments by the Fuel Research Station with the flame fougasse continued and it rapidly evolved. The fuel mixture was at first 40% petrol and 60% gas-oil, a mixture calculated to be useless as a vehicle fuel. A concoction of tar, lime, and petrol gel known as 5B was also developed. "5B was dark coloured, sticky, smooth paste which burned fiercely for many minutes, stuck easily to anything with which it came in contact and did not flow on burning." Early flame fougasse designs had a complex arrangement of explosive charges: a small one at the front to ignite the fuel