The tanks were landed by glider, where their appearance caused the Germans to cancel a counter-attack at a key moment in the battle but individually, they did not perform well.

There were several variations on the Tetrarch design, including the Alecto self-propelled gun and the Light Tank Mk VIII but none of these were used operationally by the British Army.

The prototype of the Light Tank Mk VII (A17), nicknamed 'Purdah',[7] was first developed in 1937 by Vickers-Armstrongs as a private venture, and was intended to be sold either to the British Army or to foreign militaries.

[7][10] The Mk VII design relied on an unusual steering method and a mechanical system incorporated into earlier Vickers models.

[1][9][12] The suspension system was also a new design that relied on struts with pockets of air for springing and cushions of oil for damping, and each of the wheels was independently sprung.

[11] The War Office then took the view that the tank was not acceptable as a light cruiser because the Nuffield A13 design offered better speed and obstacle crossing performance.

[2] The pre-war role of the light tank, that of reconnaissance, meanwhile had been found to be better suited to scout cars that used smaller crews and had better road abilities.

[15] The cumulative effect of these delays resulted in the production of only a small number of Mk VIIs; estimates place the final total produced to be between 100 and 177.

[2] The War Office and the Army were concluding, at this point, that light tanks were a liability and too vulnerable for use in further combat,[7] and the Tetrarch was considered to be obsolete.

[17] The demise of Tetrarch was prevented by a decision made by the War Office in mid-1941, as it was considering the equipment to be used by Britain's fledgling airborne forces, formed in June 1940 under the orders of the Prime Minister, Winston Churchill.

In a conference held on 16 January 1941, it was decided that the General Aircraft Hamilcar, currently under development, would be used to transport a single Tetrarch tank or two Universal Carriers.

The transport of 20 of the tanks to the USSR under the Lend-Lease Act depleted the number available for use by airborne forces, as did the loss of several more during Operation Ironclad, the invasion of Madagascar.

[23] The War Office also considered the Tetrarch's cooling system faulty, making the tank unsuitable for service in hotter climates, such as the Middle East and North Africa.

[2] However, the faults discovered with the Tetrarch cooling system precluded them from being integrated into units that were sent to the Middle East to participate in the North African Campaign.

The Lend-Lease program, begun in March 1941 by the United States of America to supply defensive materials to Britain and China, was therefore extended to the USSR.

As part of the program, the British government began supplying war materials to the USSR, which in early 1942, included a shipment of 20 Tetrarchs, as well as a number of Valentine and Matilda Mk I Infantry tanks.

[24] Despite these drawbacks in the Tetrarch's design, Soviet authorities believed it to be comparable to the T-70 light tank in use at the time, and decided that it was suitable to be used in combat.

[27] All three squadrons were transported to Inverary in Scotland for intensive training that focused on embarkation and disembarkation from ships and landing craft to prepare them for action in potential amphibious operations.

The Prime Minister and the Combined Chiefs of Staff decided that Madagascar should be occupied as rapidly as possible to deny the port of Antsirane to Japanese naval forces, which had recently advanced into the Indian Ocean.

The invasion plan called for an amphibious assault landing on four beaches on the west side of the tip, which would allow the British forces to advance approximately 20 miles (32 km) and approach Antsirane from the rear.

The tanks attempted to breach them, but the rocky ground made manoeuvring difficult and they could not close with the pillboxes and trenches; they engaged a number of targets with 2-pounder and machine-gun fire, but the line had to be cleared by an infantry assault later in the day.

This had been built prior to the First World War and included camouflaged pillboxes, machine-gun nests and dug-in 75 mm artillery pieces; the latter, although not specifically designed for an anti-tank role, could penetrate the armour of both the Tetrarchs and the Valentines.

[49] The primary tasks of the brigade were to bring in reinforcements and supplies, and to aid the two parachute brigades in consolidating the area held by the division; the 6th Airborne Armoured Reconnaissance Squadron was to aid in the latter task, acting as a reconnaissance force to scout out German positions and impede the movement of German forces attempting to counter-attack.

[51] It lost one tank before the formation landed when the Tetrarch broke loose of its shackles and crashed through the nose of the glider that was carrying it, causing both to fall into the sea mid-flight.

[54] The squadron retrieved all of the remaining Tetrarchs and advanced to the south of the landing zone to link up with the rest of the regiment; there, they received orders to support the 8th Parachute Battalion in the Bois de Bavent area and conduct reconnaissance duties.

[54][55] The division was reinforced by British troops who were advancing from the invasion beaches and it began to push through Normandy, while the squadron continued its reconnaissance duties.

During the first week of October 1944, the 6th Airborne Armoured Reconnaissance Regiment underwent an extensive reorganization, in which it was completely restructured, and all the remaining Tetrarchs were retired.

[7] The Mark VIII was also known as the Harry Hopkins, named after President Roosevelt's chief diplomatic advisor, and was given the General Staff design number A25 by the War Office.

These problems continued to persist into 1943, when the War Office decided against using the tank in active service; approximately 100 Mark VIIIs were produced by 1945, when production ended.

The Duplex Drive system was invented by Nicholas Straussler, and was designed to allow a tank to 'swim' through water and participate in amphibious operations.