The C&S 1008 threads brought up a mention or two of the owner's 18" gauge Hunslet "Gwen," which was brought over by retired SP/South Pacific Coast head Billy Jones back in the 50s and made its restored public debut at the 1991 CSRM Railfair. Here's a Charles Givens view of the engine at Jones Los Gatos, CA ranch about 1955, with Mt. Umunhum and a MacDermot boxcar in the background.
A bit of a back story: Billy acquired the Gwen after a fruitless trip across the pond to procure vacuum break parts for his own 18" gauge equipment. (The Brits apparently weren't keen on the idea of selling outdated technology to a Yankee). I can't recall if he sought the engine out or stumbled upon it by chance, but probably have notes on it somewhere. His Venice Railway engine was pretty well beat by this point, and his idea IIRC was to have the Hunslet as his regular engine. That idea went out the window when, upon arrival, he realized the flange profile of a full-scale industrial locomotive wasn't too compatible with a railroad built for scaled-down miniatures, causing it to ride up on switch frogs. The engine spent then about a decade in the weeds before Quentin Jervis, Frederic Shaw (who incorrectly calls the engine "Queen" in his book) and a third party "acquired" it in a lot with a good chunk of the MacDermot equipment and hauled it off to San Pedro.
P.S. With no luck on vacuum brakes, SP hostler Charlie Hoyle refitted Jones' rolling stock with its original MacDermot automatic air system. Much of this hardware still exists and is well traveled over the years; there's at least a dozen triples still floating around and Phil Reader fitted MacDermot glad hands on the brake hoses for all four PCRR "Retlaw" coaches.