 With the gradual growth of the electrification of the inner London suburban lines after 1915, the class tended to be used on stopping trains on the LSWR main line, and on services to Guildford and Reading.After the formation of the Southern Railway in 1923 the class gradually began to be used, further afield, notably in the west of England, but also on branch lines in Kent, and on the former South Eastern and Chatham Railway line between Redhill and Reading.During the 1950s a substantial number of the "push-pull" fitted members of the class was transferred to the Central Section of the Southern Region, at Brighton and Horsham, replacing worn-out D3 locomotives on the branch lines of the former London Brighton and South Coast Railway in West Sussex.