It was designed for suburban passenger work on the Potteries loop lines.

They shared components such as a drumhead smokebox which rested on the saddle and an almost identical boiler with the NSR L class.

[3] All entered the London, Midland and Scottish Railway (LMS) stock upon formation in 1923 with little modification, other than replacing the original Ramsbottom safety valves with Ross-pop type.

[1] The livery of the M class was the NSR's Madder Lake with straw lining, and NORTH STAFFORD lettering on the side tanks along with the company crest.

In LMS days all received the crimson lake passenger livery of the early LMS with large numerals on the side tanks and the company crest on the bunker, but by 1928 they were repainted in plain black with L M S written on the tanks and number on the bunker.