The SECR D class is a class of 4-4-0 tender locomotives designed by Harry Wainwright for the SECR. Initially the D class was put to work on the Kent coast and Hastings services out of London. By the 1930s the largest allocation of D class 4-4-0s was at Gillingham depot in Kent but they had by now been reduced to secondary train duties and were now carrying the livery of the Southern Railway.

At the outbreak of World War II in 1939 some of the D class were placed into storage. Then in 1941 others were transferred to Nine Elms depot. A handful were based at Redhill on the Reading-Tonbridge cross-country line.  In 1948 British Railways inherited 28 of the Wainwright 4-4-0s.

Their final years saw them concentrated at Guildford in Surrey and the last of the D class, No.31075, was withdrawn from there in 1956. One example has been preserved.