A fellow model engineer, Dr Jo Thoms, informs me that Lady Stephanie is loosely based around James Kay's engine that he installed on Lord Rothschild's estate at Dancers End, near Tring in 1867. The engine is now part of the collection at Kew Bridge. When Tubal Cain designed this model he chose to make it a single cylinder/frame engine but kept a lot of the features of the Dancers End engine. At full scale this single engine would be capable of pumping 400 gallons of water per hour up 200 feet and provided 2/3rds of a horse power with a working pressure of 30 psi.

I am working to drawings produced by Julius de Waal and downloaded from the Model Engineering Website