Hi Ray,
The photos of the engine of a 10HP bonnet car seem to show that the engine is infact one of Grouts own, or atleast not a Mason. The Mason engine had a single flat crosshead (per cylinder) and had a single water pump bracket made out of a sheet of metal, not anywhere near as strong as the pump brackets shown. The engine also seems to be fitted with an air compressor. I attach two links, one of a Grout sold on the site a few years ago, which I mentioned above, and the other of a mason engine so that you can see for yourself. George Hounslow.
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www.steamcar.net]
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www.steamcar.net]