British rocket research before Churchill's order

British work on rockets, propellants, and air defence began in the early 1930s, including a 1936 argument that rockets could become practical weapons. Calling rockets practical did not mean they were new. It meant improving an old weapon until its accuracy and performance met twentieth-century expectations. By 1937, the air-defence subcommittee preferred a 3-inch rocket to a 2-inch design and was considering a parachute-borne bomb or mine. Churchill's 1939 request for an aerial minefield pushed this research toward deployable equipment, with Vickers-Armstrongs and the Royal Ordnance Factories already involved. The deliberately bland Unrotated Projectile name obscured the weapon's purpose while describing the fact that its early rockets were not spin-stabilized.