The Great Western Railway (GWR) 2221 Class or County Tank was a class of 4-4-2Tsteam locomotive, effectively a tank engine version of the 3800 "County" Class4-4-0 tender locomotives. The two classes had different boilers, standard no 4 for the tender locomotive, and the smaller (by about 350 sq ft or 33 m2) standard no 2 for the tank. 2230 was fitted with the larger boiler when new, but this was unsuccessful and was quickly altered.
Thirty were built between 1905 and 1912 to replace the 3600 "Birdcage" Class. They were built in two batches of twenty, the batches having minor differences. In the later batch the drop in the front framing above the cylinders was curved, the cylinders were also lower and top feed was fitted from new. Later in life, the class were fitted with superheaters, and were given larger bunkers in line with other standard tank classes.
Their work was concentrated on London suburban services. They were replaced by the more versatile GWR 6100 Class from 1931 onwards, the last going in 1934. Their large four coupled driving wheels were suited to high speed running on outer suburban services but acceleration was slower than that of the six coupled, smaller wheeled locomotives.