 It showed a marked improvement in performance over his predecessor Harry Wainwright's 0-6-0 and 4-4-0 designs when tested on freight and local passenger trains.The success of the prototype encouraged the SECR management to order a batch of 15 in 1919 after government restrictions regulating locomotive production during the First World War were relaxed.Ashford locomotive works was already committed to undertaking deferred repair work however, which temporarily slowed construction of new locomotives.