Chief Mechanical Engineer of the South Eastern and Chatham Railway, R.E.L. Maunsell, laid down the design of the 'N' Class locomotive in 1914. To SECR eyes it was quite radical, as it featured outside cylinders instead of the more traditional and discreet inside arrangement. Lessons learnt resulted in various modifications, including the fitting of revised sanding gear, corrected wheel balancing and a re-styled chimney and blastpipe.
The Southern Railway continued to procure more 'N's. These had been made by the Ministry of Munitions at the Woolwich Arsenal after WWI, which earned them the nickname 'Woolworths'. A further fifteen delivered in 1932-1934 had smoke deflectors fitted and brought the class total to eighty. During WWII, use was concentrated towards the Channel ports where the heavy freight haulage capability of the class was exploited.
Nationalisation of the railways in 1948 saw British Railways acquire the whole class and re-number them in the 30000 series. The 1960's saw members of the class pushed aside as dieselisation took over. 'N' Class locomotives were moved out of the South Eastern Division to the Western and Central depots. Withdrawals started in 1962 and down-graded duties to the hauling of empty goods trains and the occasional passenger train.
Like the prototype 810, early locomotives were painted overall austerity grey. Change to the Southern Railway brought a smart lined green livery, but this degenerated to all-over black during WWII. For a brief period in early nationalisation, malachite green was the colour applied. However this reverted to black, albeit lined, in the later 1940's.