Welsh 0-6-2T locomotives

This was because the nature of the work they undertook demanded high adhesive weight, plenty of power with good braking ability, but no need for outright speed, nor large tanks or bunker as the distances from pit to port were short.

Many Welsh 0-6-2T locomotives passed into British Railways (BR) ownership in 1948 and these included (with some gaps in numbering).

The Rhymney Railway's A, M and R classes were successful designs ideally suited to hauling heavy coal trains a relatively short distance.

When the smaller railway companies were forcibly merged into the GWR in 1923, these modern 0-6-2Ts were in generally good order (some were a few months old) and had proved successful.

Included in Collett's innovations was a standard number 2 boiler which was suitable for the 5600 (and the M and R class Rhymney locomotives), complete with the traditional copper GWR safety valve casing and copper-capped chimney.