I have an old book by Renton-Laidlaw published in 1957 called Electric Model Rail Racing. The publication date and the dates you guys mention says to me it was wrtten pre- Aurora pancake as no mention is made of the pancake.
From the book it seems that the Triang Mk4(and similar lookiing designs) was the most popular motor of which Laidlaw says was originally designed to power model locomotives
Electric model racing was in its infancy then and cars ran on above track rails hence the book's title.Scalextric were just starting out and ,if I got my facts correctectly from the book ,produced the first commercial slot car racing set,where the cars ran in a slot and not on a rail.
Very interesting book.The 'slotters" in those days had to virtually build cars from scratch out of balsa wood and brass.Tyres were from static models.Various types of guide and steering were experimented with.
The book also gives detailed plans, materials required (and a suppliers list)in order to construct models of cars like Bughatti and Ferrari .
The book has also got a chapter about diesel powered cars on rails. Engine capacity about 0.5cc. Scale about 1/12 or bigger.I wonder if this class is still around.Doubt it though.
Those were the days or what?