Design and development
From early in the war, there had been experiments with mounting flamethrowers on British vehicles; leading to vehicles such as the Cockatrice, Basilisk and the Wasp (the latter being a flamethrower on a Universal Carrier). The Churchill Oke, a flamethrower carrying Churchill Mark II developed by a Royal Tank Regiment officer, was tested operationally on the Dieppe Raid. Parallel development work was carried out by the Petroleum Warfare Department, AEC and the Ministry of Supply (MoS) on Valentine tanks. The Department of Tank Design preferred the Churchill, which was the Infantry tank successor to the Valentine, as a basis for further work.
General Percy Hobart saw the Crocodile demonstrated in 1943 and pressured the MoS to produce a development plan and the Chief of the General Staff added the flamethrowers to the 79th Division plan.
The flamethrower equipment was produced as a kit that REME workshops could fit in the field, converting any available Churchill Mk VII. The conversion kit consisted of the trailer, an armoured pipe fitted along the underside of the tank, and the projector, which replaced the hull mounted Besa machine gun. The Crocodile was therefore still able to function as a gun tank with its turret mounted Ordnance QF 75 mm gun.
Of the 800 kits produced, 250 were held in reserve for possible operations against the Japanese. The remainder was sufficient for producing three regiments of tanks as well as training and replacements for battlefield casualties.
400 imperial gallons (1,800 l) of fuel and the compressed nitrogen propellant, enough for eighty one-second bursts, were stored in a 6½ ton detachable armoured trailer towed by the Crocodile. The trailer, connected to the tank by a three way armoured coupling, could be jettisoned from within the tank if necessary.
The thrower had a range of up to 120 yards (110 m) although some sources quote 150 yards (140 m). The pressure required had to be primed on the trailer by the crew as close to use as feasible, because pressure could not be maintained for very long. The fuel was used at 4 gallons per second; refuelling took at least 90 minutes and pressurization around 15 minutes. The fuel burned on water and could be used to set fire to woods and houses. The flamethrower could project a "wet" burst of unlit fuel, which would splash around corners in trenches or strongpoints, and then ignite this with a second burst.