They were a freight and light mineral development of the 3300 Bulldog and 4100 Badminton classes, both 4-4-0 locomotives.

Therefore, the design was adapted and became a 2-6-0 type; the resulting locomotives were used for hauling coal trains between Aberdare and Swindon.

Five Aberdares (2640, 2648, 2649, 2652 & 2657) withdrawn in early 1939 were not cut up but stored as Second World War reserves.

Their withdrawal began again in 1944 until the last member, number 2667, was withdrawn in October 1949.

This article relating to steam locomotives operated in the United Kingdom is a stub.