  under the british rail tops computer system, class 405 was allocated to surviving examples of the southern railway (united kingdom) 4-sub class electric multiple units built between 1941 and 1951. details of the origins and history of that class are found in the sr class 4sub article. ==history== 179 out of the 184 new units constructed between 1946 and 1951 were still surviving at the introduction of the tops computer system in the early 1970s,williams and percival (1973). but were expected to have limited working lives. all surviving units were allocated to class 405, but divided into two sub-classes. sub-class 405/1 included the former southern railway sets numbered between 4112 and 4387, and sub-class 405/2 included the former british railways sets built after 1949 and numbered 4601 and 4753.williams and percival (1973). all had been withdrawn by 1983. ==preservation== class 405/2 unit number 4732 is currently stored at the electric railway museum, warwickshire. ==references==  ==external links==   simple:british rail class 405
British_Rail_electric_multiple_units Southern_Railway_(Great_Britain)_electric_multiple_units