 The latter order was cancelled after the Southern Railway was taken into public ownership, to allow trials to be carried out on the prototype.Each of the two bogies had three cylinders, with the driving wheels connected by chains enclosed in an oil-bath, based upon Bulleid's chain-driven valve gear on his Pacific locomotives.The valve gear used the unusual sleeve valve arrangement that was also tested on the ex-LB&SCR H1 class "Hartland Point" in parallel with the construction of the first Leader locomotive.