Not quite a direct answer to your question, but i have a set of magazines from the 70's titled 'History of Model and Miniature Railways' which came out as a periodical forming a boxed set of 45 magazines. Part 5 contains an article written by R.A. Symes-Schutzmann on the building of two Gauge 1 diesel locomotives, one a diesel-electric based on a Brush Type 4 and the other a diesel-hydraulic based on the Hymek loco. Both were powered by a Taplin Twin engine, the Type 4 having the engine driving a motorcycle generator which in turn powered axle-hung 12V traction motors. The Hymek had an actual hydraulic drive. Not sure if these locos still exist. The design and construction of these two locos was credited to the Onslow Works Team. No idea if they still exist. I suspect the bodies were hand-made. No idea if 1:32 scale kits or individual parts for such locos are available.