[1] Development began at Vickers-Armstrongs in 1956 as a private project to give the company's Weybridge Guided Missile Department something to do after the cancellation of Red Dean.

By 1960 it had completed development and an extensive testing program, but the War Office remained disinterested as they wished for the Weybridge department to be disbanded as part of the ongoing formation of British Aircraft Corporation.

On several occasions the Office explicitly stated they did not want to provide any encouragement to the team as this might make it harder to close the division down in the future.

After considerable debate spanning several years, the project eventually won an initial order as it was the only suitable design to arm the Ferret armoured car.

The last, the Red Dean/Red Hebe air-to-air missile was so delayed and over-designed that the company began to have a bad reputation with the Ministry of Supply, especially with John Clemow, the Director.

[2] When Red Hebe was cancelled in the aftermath of the 1957 Defence White Paper, the company's guided missile department had no remaining projects.

[2] Unwilling to give up on the missile field, George Edwards led an effort to find a new project that could be undertaken with company funds alone.

[3] For any given level of penetration, HESH required much more explosive, and Malarka's need to deal with main battle tanks demanded a 57 pounds (26 kg) warhead.

Combined with the long desired range, 3,000 yards (2,700 m), the missile ended up being 206 pounds (93 kg), far too heavy to make it man portable.

[3] The same basic guidance system was used by most contemporary designs like the ENTAC, SS.10 and SS.11, and the Cobra, as well as the US Army's experimental Dart that was not put into production.

[6] Sure that a contract for a Malkara replacement would be forthcoming, Vickers hired John Clemow, their critic, along with Howard Surtees, to head up the new effort.

Development began in late 1956 under the model number 891[4] and given the name Vigilant, for VIsually Guided Infantry Light ANti-Tank missile.

This allowed the missile to spin along its long axis, which was used to even out any asymmetry in the rocket thrust and ensure it flew in a relatively straight line.

[b] By this time the original germanium transistors from Texas Instruments were replaced by silicon versions, which were both less expensive and much less sensitive to temperature.

[13] Testing also demonstrated that the guidance wires were not strong enough and tended to break, leading to extensive experiments to find a solution.

This was originally in the form of a "Sten gun" like arrangement that was designed to be fired from the hip during the testing phase, but modified for use while prone for the production version.

After some experimentation a new design was developed used that used a cup-like arrangement that the operator inserted the front of their thumb into while their fingers held a pistol-like grip.

In this version, guiding the missile down was accomplished by pulling the controller down, as opposed to pushing forward as on a conventional joystick, and the problem of incorrect guidance immediately fell to only 5%.

Testing at Redstone noted that the flare was too difficult to see at long range in bright sunlight,[c] and a more powerful model was developed.

Duncan Sandys strongly suggested that future orders for weapons would only be given to larger companies, forcing the merger of smaller firms.

[24] The memos continued to fly and it was not until 4 August that the War Office finally conceded the point and decided to offer small contracts to keep the effort going.

The news was made public on 26 August, the newspapers noted the company has spent nearly £1 million on development and the projected price was only nearly £500 per unit.

[25] The matter of a wider purchase remained open and it was not until 24 November 1961 that clear signals from the Ministry of Aviation suggested they were going to fund production.

By this time the merger of Vickers into BAC was starting in earnest, and through the early part of 1962 the Weybridge design office closed with most members moving to Stevenage.

This was effected primarily by moving the contact fuse to the end of a "probe" that extended forward from the front of the missile after launch,[29] providing more stand-off distance in which an improved metal jet could form.

[29] In testing, British Aerospace found the CML warhead was able to penetrate 17 inches (430 mm) of typical single-layer tank armour.

These are slightly longer than the wings and serve double duty in connecting the control signals from the wires at the rear of the missile to the guidance system and gyroscopes.

[9] At the extreme rear of the missile is a canister containing the outlet pipe for the rocket in the center, with a molybdenum nozzle,[11] and a magnesium flare wrapped around it.

The man-portable configuration consists of a launcher which doubles up as a transport container, a combined sight and controller, a battery and a 63 meter long cable.

The rear cap is removed entirely, it contains the spool holding the cable that attaches to the sighting system or selector box.