Staff Writer (Updated: 4/5/2016):
The British Type E became the T-26 in the Soviet inventory and brought about as a light infantry tank. The initial production version featured twin turrets in a distinct World War 1 style layout, each turret mounting a single 7.62mm anti-infantry machine gun. This version was known as the T-26A1 and were basically carbon copies of the British production models. From there, the previously Vickers design evolved into several variants starting with the base T-26A, all centering on increased crew protection and the mounting of evermore potent weapons. Power was derived from a single GAZ-type T-26 8-cylinder gasoline engine that delivered some 91 horsepower. The system would be crewed by 3 personnel. The T-26A2 followed shortly there after and became the first all-Russian production models armed with Soviet machine guns.
One T-26 model appeared with a 1 x 7.62mm and a 1 x 12.7mm (.50 caliber) machine gun array whilst another mounted an additional 27mm cannon in place of the aforementioned heavy machine gun. A 37mm main gun was fitted to the T-26A-5. The T-26B model series became the definitive T-26 tank as the twin turret design was dropped in favor of a more traditional single turret layout. This single turret was initially fitted with the 37mm main gun of the T-26A-5 but was later upgraded to a more potent 45mm variety.
The pinnacle T-26 design came with the arrival of the T-26S series. This particular series saw a change from riveted construction techniques to welded designing. Not only did this improve the overall protection of the tank turret but it also removed the deadly effect of having rivets blown clean from their holes from inside in the event of a direct hit by the enemy. The T-26 was spawned into other battlefield roles, more notably the addition of bridging tanks (in the ST-26 model), command vehicles (in the T-26A-4V and T-26B-2V models) and flamethrowing derivatives (all tanks beginning with the "OT" designation. An attempt was made with mounting a 76.2mm main gun to the turret which would go on to become the AT-1.
T-26s entered service in 1931 and were in play until 1942, by which time they were wholly obsolete. Captured T-26s in German hands were modified as gun carriers (75mm PaK 97/38 light tank destroyers) while Russian use of their own system was interupted after their factories were overrun. In any case the T-26 was reported to be a stable system without much fanfare. It was adequate for the role but hardly an impressive machine. It did operate in combat conditions from the Spanish Civil War and combat against German, Japanese and Finnish forces alike, earning the Russians some much-needed experience in the realm of tank design and - more importantly - mass production of military systems.