[1] They were delivered new to the Welshpool and Llanfair Light Railway in 1902, as No.1 The Earl and No.2 The Countess, where they continue to run today.

The 2 ft 6 in (762 mm) gauge Welshpool and Llanfair Light Railway was opened on 4 April 1903 to aid economic development in a remote area, never making a profit.

The line was built through difficult country, having a great number of curves in order to reach the summit of 600 ft (180 m).

This meant that the engines had to be built to a compact and sturdy design capable of handling trains on the steep gradients.

When taken over by British Railways, their shunting bells and chopper couplings were removed, and were repainted black.