The N15 Class, introduced in 1918 from a design by Robert Urie, was also known as the King Arthur Class, being named after persons and places associated with the legend of King Arthur and the Round Table. This class of two cylinder 4-6-0 passenger steam locomotives proved to be one of the most successful during the post-grouping era of 1928-1948, with 74 locomotives being built during this time.
The whole class was built in a total of six batches, with the first two batches being built at the London & South Western Railway's Eastleigh Works between 1918-19 and 1922-23. Carrying the characteristics of Urie's stove pipe chimney, Drummond style of cab and inspired by the shape of the H15, the first batches of locomotives became known as 'Urie Arthurs'.
Upon assuming the position of CME of the Southern Railway, Richard Maunsell built a third batch of ten locomotives at the Eastleigh Works and these became known as the 'Eastleigh Arthurs'. Maunsell's batch incorporated a small number of significant modifications including changes in the draft, valve gear, chimney, blastpipe and an overall increase in boiler pressure that significantly improved the performance.
In 1924 two more batches were ordered from the Scottish based North British Locomotive Company. These 30 locomotives, referred to as 'Scottish Arthurs' were built to the Southern Railways new composite loading gauge and were connected to eight wheel bogie tenders, which had a 5,000 imperial gallon capacity.
The last batch of 15 locomotives were built at Eastleigh between 1926-27 and adopted a six wheel 3,500 imperial gallon tender. Despite the order the batch was never completed, with the last locomotive being replaced by the prototype of the Lord Nelson Class of locomotives. Having proved to be one of the greatest designs of its day, the King Arthur Class combined reliability with impressive performance.