Two Bo-Bo electric locomotives were built to operate the Newcastle Quayside branch in 1905. The frames and bodies were constructed by Brush Engineering in Loughborough, who acted as sub-contractors to British Thomson-Houston Co. who supplied the electrical equipment. The track was fitted with a conductor ("third") rail in the tunnels where there was insufficient overhead clearance. It was also used when travelling to/from Heaton shed. For safety reasons, overhead wires were used in the yards at each end of the branch.

Described simply as "0-4 4-0" by both the NER and LNER, these two engines did not have an official classification until 4th October 1945 when they were designated as Class ES1 (Electric Shunting 1). Despite the lack of an official classification, early photographs also show them with the words "CLASS ELECTRIC 1" on their buffer beams.

British Railways (BR) renumbered Nos. 1&2 as Nos. 26500 & 26501. Both locomotives continued to work the Quayside branch until they were replaced by an 0-6-0 diesel on 29th February 1964. The ES1s were put into store at South Gosforth car sheds and withdrawn from stock in September 1964. No. 26501 was sold for scrap in April 1966. No. 26500 was stored at Rugby before entering preservation as a part of the National Collection in 1968.