Another point of view was espoused by John Gray who set out to improve efficiency and increase the pressure in shorter boilers using single drivers instead of coupled wheels.

The long boiler design with coupled wheels continued for slower heavier work.

The small size of the firebox would seem remarkable in later years, but the engines were ideal where trains might spend long periods standing, waiting for a path, or when shunting.

A minimum amount of fuel would have delivered sufficient heat to the large boiler to start heavy loads.

Having travelled an official mileage of 908,984 miles (1,462,868 km), locomotive number 1275 is preserved at the National Railway Museum in York.