The original locomotive now residing at the Severn Valley Railway, is a Hawksworth design 0-6-0PT tank engine built in 1949.
“What’s interesting is that the physics of the 1501 Steam Engine does not scale, so you have to make very significant changes to the boiler design. There are approximately ten times as many tubes in a full sized boiler. Also, scale fittings and bolts become too small in some cases to be practical, so changes have to be made to hide the fact that some of the bolts are mockups. This is all part of the fun of doing it!”
Roger Froud, Amytech (UK) Ltd.