4mm and 7mm:
A number of projects, including W France 1909, W Midlands 1963, Chester 1959 (non-portable) and, in progress, S London (LSWR) 1882 - have exhibited in Yorkshire with portable layouts
Currently loco building in 7mm and exhibiting Coton hill MPD (WR/LMR 1960s) in 7mm around Yorkshire.
Back in 66 or 67, I was hauled from Manchester Exchange to Leeds (on a Lpool - Newc) behind a Sulzer type 4, inside which was coupled a Caprotti standard 5 to provide heating. The 5 was the Exchange pilot and was very low on water when it got to Leeds!
Russell J H, Pictorial Record of Great Western Engines OPC 1978, Vol 2, p.234 diag 606 is a drawing of the frames while fig 609 is a foto of it coupled to 5068.