The Bristol Bloodhound is a British surface-to-air missile developed during the 1950s as the UK's main air defence weapon, and was in large-scale service with the Royal Air Force (RAF) and the forces of four other countries.
Designed to provide a last line of defence for the V bomber bases to destroy any Soviet bombers that got past the defending Lightning interceptor force operating over the North Sea, the Bloodhound Mk. I entered service in December 1958, and began to be replaced by the much more capable Mk. II starting in 1964. The last Mk. II missile squadron stood down in July 1991, although Swiss examples remained operational until 1999.
The Bloodhound Mk. II was a relatively advanced missile for its era, roughly comparable to the US's Nike Hercules in terms of range and performance, but using an advanced continuous-wave semi-active radar homing system, offering excellent performance against electronic countermeasures, as well as a digital computer for fire control that was also used for readiness checks and various calculations. It was a relatively large missile, which limited it to stationary defensive roles similar to the Hercules or the Soviets' S-25 Berkut, although the Swiss operated theirs in a semi-mobile form.
Bloodhound shares much in common with the English Electric Thunderbird, including some of the radar systems and guidance features. Thunderbird was smaller and much more mobile, seeing service with the British Army and several other forces. The two served in tandem for some time, until the shorter-range role of the Thunderbird was replaced by the much smaller and fast-acting BAC Rapier starting in 1971. Bloodhound's longer range kept it in service until the threat of bomber attack by the Soviet Union disappeared with their dissolution in 1991.