In 1946, the Tasmanian Government Railways (TGR) put out a request for tender for the construction of five to ten diesel-electric locomotives, which was successfully awarded to English Electric.

No members of the class were named after entering service, however X16 carried a commemorative Festival of Britain plate after it was displayed at that exhibition in 1951.

Their light axle loading made it possible for them to work on a wide variety of lines, and for many years after their introduction the X class were the dominant freight-hauler on Tasmanian railways.

[7] Starting in April 1954 and working until July 1978, the Tasman Limited, Tasmania's premier passenger train, was hauled primarily by the X class.

As a result, five had their generators and control equipment modified between 1961 and 1970 to give two stages of field weakening and were reclassified as the XA class.

[8] Upon their initial construction and delivery, all units of this class were painted Brunswick green; however, this colour tended to blend into the Tasmanian countryside, resulting in several accidents at level crossings.

[8] After control of Tasmanian rail lines was passed to Australian National in March 1978, most units retained their old yellow livery, but with ANR signwriting.