Have a Taste
Soviet military intelligence had little interest in British light tanks before the war. In April of 1941, GABTU knew about the Light Tank Mk.VI, Mk.I and MkIII cruiser tanks, the Mk.I infantry tank, and some kind of "heavy tank model 1940". Even in September, when negotiations about supplying the USSR with British vehicles were underway, the information on available tanks was sparse. The Light Tank Mk.VI and Light Tank Mk.VII "Tetrarch" got mixed up into one tank. The resulting "light Vickers tank" had a 37 mm gun with a coaxial machinegun, maximum armour thickness of 17.5 mm, weighed 8.5 tons, and had a maximum speed of 30 kph.
Data on tanks loaded on the first convoy in late September of 1941 is even more interesting to researchers, as it contains a "Light Tank Mk.8". This index was carried by the "Harry Hopkins" tank, but the characteristics listed show that it is undeniably a Tetrarch. The document said that 20 such tanks will arrive with PQ-1, but instead a batch of 20 Matildas and Valentines was sent. Supplies of lighter tanks were paused for the time being.
In early October of 1941, thanks to military intelligence, GABTU received characteristics of nearly all tanks built by Great Britain and the United States. In early December, GABTU received detailed information about production of British tanks. The numbers retrieved match up very well with modern data from British sources. The first 15 Mk.VII tanks were built in the fourth quarter of 1940, 30 in the first quarter of 1941, and 20 in the third quarter. 35 more tanks were awaited before the end of the year.
These numbers match perfectly with Tetrarch production numbers. Their registration numbers range from T.9266 to T.9365, or 100 tanks overall. Intelligence reports indicated that no tanks were planned for production in the first quarter of 1942, which indicated that production was being shut down. Reports also described plans for a new Light Tank Mk.8 with a mass of 10 tons and thicker armour.
- The engine works well, but the cooling system has a drawback that does not allow the water to be fully drained without removing the engine. In addition, the cross-section of the drain pipe is 4 mm, which is insufficient, quickly clogs, and freezes. Work in the winter even on the Transcaucasian Front requires antifreeze.
- Many parts and assemblies are not robust, and break down even with light use on good roads.
- The wheel carriers are not robust enough and tend to crack in the corners.
- The drive shaft gear wears out quickly.
- The armour has the following drawbacks:
- The turret roof is poorly held, the seven 4-5 mm thick brackets can be torn off with a crowbar.
- The hatch lock is loose.
- Openings are present in the turret and rear that could be easily avoided, strengthening the tank against bullets and incendiary fluid.
- The layout of certain components (gearbox, differential, brake drums) is poor, as they are located underneath the engine and require its removal for maintenance.
- Access to the idler wheel gear carrier is difficult.
- The track and track links do not have good traction with the ground and slip often on wet or snowy roads.
- The MK-7 tank has a powerful 120 hp engine and a high speed.
- With its weak suspension, gearbox, and final drive, it must be only used on good (not rocky) dirt roads.
- The tank turns poorly and has to be used on flat terrain where sharp turns can be avoided.
- The tank has weak armour (much weaker than domestic light tanks) which offer poor protection for the crew.