Initial livery after nationalisation in 1948 was British Railways malachite green and "Sunshine yellow" lining and lettering, with British Railways on the tender. No. 34090 "Sir Eustace Missenden, Southern Railway" was given commemorative malachite green livery that included green-painted wheels with yellow rims and the early British Railways crest on the tender. The Bulleid numbering system was temporarily retained on the first seventy locomotives with the addition of an "s" prefix (e.g. s21C101). The classes were given several power classifications in their careers, beginning with 6MT (Mixed Traffic) in 1949. In December 1953 they were reclassified 7P 5FA, the "A" denoting brake power when used on unfitted (non-vacuum braked) goods trains. The rebuilt locomotives retained this classification until all received the classification of 7P6F between November 1957 and November 1961.