In the 1930s, the British manufacturer Vickers produced a tank design called the 6-Ton. When the 6-Ton wasn't picked up by the British army, the Russians bought the license and started to produce it under the name T-26. This tank saw action throughout the 30's as one of the leading tank designs. Unfortunately by the time WW2 came around, it had seen better days and was outclassed by anti-tank weapons. That didn't stop it from being widely used in the defense of Russia.With over 11,000 produced across 23 production variants, plus a lot of experimental iterations, it was in use for a long time. Spain and Finland continued to use them well after the war had finished.
Here we have a Russian T-26 displaying Finnish markings.