Great show Philip! And definitely an idea that I will have to steal when exhibiting at a show. You could have a full table, half a dozen engines and only have to worry about feeding two boilers.
I plan to make the above display a centerpiece at the Earl Shilton Rally this year showcasing the economy of steam, which i hope will prove popular as well as educational. Look forward to see what you come up with your own display Nick.
I guess if you had an engine with either an 1" or 1 1/4" bore you could make it a quadruple expansion engine!