A Class 7E locomotive is being kept company by a couple of steam generator wagons. When steam locomotives started making way for electric and diesel traction in the 1950's, vapor wagons were introduced to provide steam heating in passenger coaches.
Classes 7E, 9E, 11E, 14E, 15E, 19E, 20E and 21E.
7E & 11E are 25kv AC locos. 9E & 15E are 50kv AC locos and the remainder are dual-voltage (25kv AC & 3kv DC).