Lister and Porter
Yes, you are quite right. That is a Bachmann 0n30 0-4-2 Porter in the background. If you do your math, at 1:48 scale it works out to be a half sized model of the real thing for its 1:24 engineer Jon. The rolling stock behind it are Chivers shorty ones.
In the foreground is my scratchbuilt 1:24 model of a Lister driven by Heidi. This is powered by a Bachman 0n30 trolley mechanism. The two wagons the Lister is pushing are Sidelines resin kits by Steve Bennett. This image was taken in the early days of the layout.