Prior to 1862 the companies that had built the various parts of the network operated locomotives from a variety of engineering companies. Generally the wheel arrangements were and for most classes of locomotives. It was not until 1850 that the Eastern Counties Railway under Gooch built a locomotive at the then newly opened Stratford Works. Number 20 was the first of a class of six locomotives (although three more were also built by R B Longridge and Co of Bedlington, Northumberland). Slightly bigger improved versions of the class followed in 1853 and 1854.