Panjandrum, also known as The Great Panjandrum, was a massive, rocket-propelled, explosive-laden cart designed by the British military during World War II. It was one of a number of highly experimental projects, including Hajile and the Hedgehog, that were developed by the Admiralty's Directorate of Miscellaneous Weapons Development (DMWD) in the final years of the war. The Panjandrum was never used in battle.
The DMWD had been asked to come up with a device capable of penetrating the 10 ft (3.0 m) high, 7 ft (2.1 m) thick concrete defences that made up part of the Atlantic Wall. It was further specified that the device should be capable of being launched from landing craft since it was highly likely that the beaches in front of the defences would act as a killing ground for anyone attempting to deliver the device by hand. Sub-Lieutenant Nevil Shute calculated that over 1 long ton (1,000 kg) of explosives would be needed in order to create a tank-sized breach in such a wall. The delivery method for such a quantity of explosives posed a significant problem, and one of the concepts discussed ultimately resulted in the construction of the prototype "Great Panjandrum". The proposed device was composed of two wooden wheels, ten feet in diameter with steel treads a foot wide, joined by a central drum fitted with the explosive payload. It was to be propelled by sets of cordite rockets attached to each wheel. It was predicted that when deployed with a full 4,000-pound (1,800 kg) load, Panjandrum would achieve speeds of around 60 mph (100 km/h), simply crashing through any obstacles to reach its target. The name "Great Panjandrum" was chosen by Shute as a reference to Samuel Foote's famous extempore nonsense paragraph (though Foote's term was actually "the grand Panjandrum"), and in particular to its closing line "till the gunpowder ran out at the heels of their boots".
The prototype was secretly constructed at Leytonstone and transported by night to the testing grounds at Westward Ho!, Devon. However, once there, the secrecy surrounding the project broke down, as the beach chosen as a test site was also a popular destination for holidaymakers; from the first test on 7 September 1943 onwards, every trial was witnessed by large citizen audiences despite the DMWD's warnings concerning the safety of the weapon. Since nothing remotely resembling the Panjandrum had ever been constructed before, the trials began with trepidation—only a handful of cordite rockets were attached to the wheels, and the payload was simulated by an equivalent weight of sand. When Shute gave the signal, the rockets were ignited and the Panjandrum catapulted itself forward, out of the landing craft used as a launchpad, and a fair distance up the beach before a number of the rockets on the right wheel failed and the weapon careered off course. Several further attempts were made with more and more rockets, but on every occasion the Panjandrum lost control before reaching the end of the beach.