zSR King Arthur 741 Big 4 CentHOR R30273 Hornby SR, N15 'King Arthur Class', 4 6 0, 741 'Joyous Gard': Big Four Centenary Collection Era 3 2023 Catalogue 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