The prototype is an outside cylinder 0-4-0 side tank with outside Walschaerts valve gear. It was designed by A.J. Hill and the first one was built in 1913 at Stratford numbered 227; it was classed B74 by the Great Eastern Railway. In 1914 two more were built to a lower loading gauge to suit Devonshire Street and Mile End Goods Yards and to work in the Pepper Warehouses at Canningtown. They were painted grey and had brass topped chimneys. The last one was built in 1921 and spent all its life as a service engine at Stratford Works. In 1931 number 227 was cut down to the specification required for Devonshire Road and Mile End Yards. They were well known for rocking about due to their short wheel base and large overhang and often knocked off the cylinder drain cocks when travelling over paved lines found in dockyards and streets. The last one was withdrawn in 1963. The 5" gauge version has been considerably refined since the original design was produced to bring it much closer to scale without sacrificing either strength of construction or power of the locomotive.