 Although the S15 was superior in freight haulage capacity and operational economy, the N class’ good all-round performance on passenger and freight meant that the type was adopted as the company's standard mixed-traffic design.The Southern Railway subsequently bought fifty "Woolwich" kits for assembly at Ashford between June 1924 and August 1925.These were identical to the SECR batch and were given numbers in the series A826–A875.