In 1949 English Electric set up a Guided Weapons Division at Luton. The aim was to develop a Surface to Air Guided weapon that would accompany the British Army in the field. As theStage air defence plan evolved the English Electric SAGW became part of the Stage I system to provide air defence coverage for the Army with a range of 20 miles. This weapon was assigned the colour code "Red Shoes" by the Ministry of Supply.
The test programme involved a few development vehicles, with the aerodynamics being proved by the D.3 and D4 test vehicles. The main development work was performed by the LTV, Luton Test Vehicle.
Red Duster was to be a rocket propelled mobile missile guided by pulsed radar, AMES Type 83, calledYellow River. The initial sustainer was a liquid fuel rocket engine, but the Army did not want such fuels in the field so a solid rocket motor sustainer was fitted. Various sustainers were applied including the Albatross, Ratcatcher, Elkhound Wolfhound and Smokey Joe. Red Shoes also used a quartet of Gosling boost rocket motors for launch. On entering service with the Army this became Thunderbird I.
As the air threat changed and radar development progressed, it was decided to fit Red Shoes with Continuous Wave radar. This would confer improved performance in the face of ECM and much improved low-level capability. This was to be Red Shoes with a CW seeker using AMES Type 86 Indigo Corkscrew radar and was renamed Green Flax. At some point the paperwork was lost and as a security measure the name was changed to Yellow Temple. This would become Stage 1 1/2 and was assigned entered service asThunderbird II.
A further name, VR.725, was applied after the Ministry of Supply was dissolved and was applied to a version using the AMES Type 88 Tactical Control Radar and Type 89 height finder radar. These radars had been developed under the colour codeGreen Ginger, but were called AD.11 and AD.12 respectively in British Army Service. This entered service as Thunderbird II.