Swingfire was a British wire-guided anti-tank missile developed in the 1960s and produced from 1966 until 1993. The name refers to its ability to make a rapid turn of up to ninety degrees after firing to bring it onto the line of the sighting mechanism. This means that the launcher vehicle could be concealed and the operator, using a portable sight, placed at a distance in a more advantageous firing position.

Swingfire entered operational service in 1969 and underwent several major upgrades during its time in service. It was used on a number of vehicles including the FV438, FV102 and several truck mountings including the Land Rover and Ferret armoured car. Concepts adapting it to helicopters, tanks and even hovercraft went nowhere. Swingfire remained in service on the FV102 Striker until 2005 when they were retired in favour of man-portable missiles.

The British Army was among the first to introduce a heavy anti-tank missile when they introduced the Malkara in 1958. The Malkara had a number of problems, among them that the missiles had to be raised into the line of sight for firing, and left a line of smoke from its rocket motor that lingered long enough to point directly back to the launcher. Additionally, the guidance system was difficult to use and had limited performance against moving targets. Malkara was nevertheless purchased for the airborne infantry to allow them to deal with Soviet armour at long range.

Desiring a more capable weapon, the Ministry of Supply funded the Orange William development at Fairey Engineering Ltd beginning in 1954. The idea behind Orange William was that the launcher and guidance systems were separated by up to 2 kilometres (1.2 mi), allowing the launcher to remain far behind the front line while the small and heavily camouflaged guidance vehicle moved forward where it could see the enemy. Unfortunately, testing demonstrated the selected guidance system was easily blocked by smoke and dust, making it ineffective on the battlefield. Through this same period, the Army was developing the Royal Ordnance L11 120 mm gun for the Chieftain tank, as development continued it appeared it would be able to defeat any Soviet tank design. The need for a heavyweight missile was less pressing and development of Orange William was cancelled in September 1959.

Through the same period, a much lighter man-portable weapon was also being developed, the Vickers Vigilant. Based on the experience with Malkara, Vigilant introduced a much improved guidance system. While it was still manual, requiring the gunner to watch the missile approach the target, it used a new method of sending corrections to the missile that was far easier for the gunner to use, especially against moving targets. Vigilant went on to see widespread use in several nations including the United States.

The basic idea of under-cover fire remained of interest to the Army after the cancellation of Orange William, and the Royal Armament Research and Development Establishment (RARDE) was given £250,000 a year to continue research into the basic concepts. As part of the resulting Project 12, they developed two basic concepts, Quickfire and Swingfire. The former appears to be a fast-action weapon, but few details have been made public. The latter was designed to allow it to be fired from under cover, like Orange William. As the company already had experience in the indirect fire role, and fearing it would otherwise lead to the breakup of their missile team, Fairey was issued a new development contract in October 1959.

The basic idea of the Swingfire concept was that thrust vectoring of the rocket exhaust allowed the missile to make extreme maneuvers, including a right-angle turn immediately after launch. This was especially useful in urban settings like Berlin; the gunner could take the sight up to 100 metres (330 ft) from the launcher and position themselves along potential lines of approach, while the launcher parked down a side street or alleyways. The crew would then dial in the distance to the main line of fire and its angle relative to the launcher, and the missile would travel that distance and then turn, flying past the gunner and into his sights. The missiles could be fired without the launcher ever exposing itself to the enemy, and the gunner could remain hidden in a foxhole or building. While the rocket smoke would still give away the rough location of the launcher, the enemy would be unable to return fire against the hidden launcher and would have no idea where the gunner was located.

As the Warsaw Pact greatly increased its number of tanks during the 1960s, the long-range missile was once again considered important. The Soviet plan was to simply overrun NATO forces using sheer numbers, so a weapon that could attrit these forces before they reached friendly forces was highly desirable. The US Army was equally interested in such a system, and in July 1961 the two countries signed the Rubel-Zuckerman Agreement for further development. Under this plan, the US would concentrate on short-range rapid-fire weapons, while RARDE would continue Swingfire development for the long-range role. Of the several concepts studied in the US, the BGM-71 TOW was ultimately selected. TOW used a semi-automatic guidance system that was very easy to use and capable of easily tracking moving targets, but had limited accuracy in long-range use and had to fly directly at the target and thereby expose the gunner to attack.