The Standard Four Mogul was essentially a standardised version of the LMS Ivatt Class 4, and was primarily intended for freight use.

The cylinder covers of engines built early in the programme of construction were fitted with "screw-in" type pressure relief valves.

From September 1955 revised cylinder covers were introduced for renewals incorporating "bolt-on" type pressure relief valves.

Apart from a pair allocated to Leicester, most of the London Midland Region's batch of 15 spent their working lives in the Liverpool, Manchester and Preston areas.

[citation needed] At first the North Eastern Region scattered its 13-strong allocation far and wide: Darlington, Gateshead, Hull, Sunderland and York.

Later all were concentrated at either Kirkby Stephen or West Auckland to work over the Stainmore route whose viaducts had severe weight restrictions.

They worked coal trains as well as passenger services and were a regular choice for excursions from Tyneside to the Lancashire coast resorts.

The Scottish examples were mainly concentrated in Ayrshire and around Glasgow, and at one time Corkerhill depot was home to ten of the class.

Four engines have survived into preservation, all four built at Horwich Works and rescued from Woodham Brothers scrapyard at Barry Island.

After completion of its most recent overhaul in 2014 it once again had a mainline certificate but was restricted between Battersby and Whitby on the Esk Valley Line.