 Taking inspiration from the 3-cylinder locomotives designed by Vincent Raven for the North Eastern Railway, Holcroft suggested that all three cylinders and associated steam passages should be cast in a single block, with rectangular holes cut into the frames to enable the outside cylinders to project through them.However, the SECR’s established practice of using outside steam chests on locomotives with outside cylinders prevented this, and the design team resorted to cutting a gap in the frames to accommodate the outside cylinders, which were then secured in place with a bolted splice plate.Production limitations at the Ashford works foundry also prevented the manufacture of a single casting that incorporated all three cylinders.