 The Southern Railway had also upgraded the permanent way on many of the former SECR routes by 1929, removing many of the weight restrictions that inspired the use of the Holcroft gear in the first place.Maunsell was therefore free to use three separate sets of Walschaerts valve gear driven by the centre driving wheels and the crank axle, a system that was easier to maintain due to the wide availability of parts.The new locomotives were completed between March and November 1930.