It was the brand of the builder Gustavus Green, known as the "The Green Engine Co. Ltd".

“Drawing of a Green engine by Angelucci y Matricardi” (PiP)

"The same engine in an ad"

-At the 1909 Paris Airshow, and the Olympia Show in London in March 1910, they  presented the four-cylinder engine of the picture below.

“4 cylinder”

-We show an ad of the Green engine for the Industry Show held at the Olympia in 1910.

As we deduce, the Green engine is made according to the patents of "Motor Patents Syndicate Ltd." that in turn belongs to "The Aster Engineering Company, Ltd".

“Green aviation engine ad”

-There was the water-cooled C-4 giving about 32 hp at 1,200 rpm.

“Schematics of a 4-cylinder Green engine”

-It had a camshaft on the cylinder heads and some strange bulky rockers. The carburetor did not have a float.

-As we see in the diagrams, the central cylinder shaft did not coincide with that of the crankshaft.

“Four-cylinder side view”

-The engine in the picture above clearly shows its three times bifurcated intake manifold.

-Another thing that we see clearly here, is that the carburetor is heated by the engine water: a duct leaves the pump, passes around the carburetor body and goes to the cylinder bases.

-The C-4 engine was used on the Dunne D-5, giving the order of 30/40 hp at low rotations, 1100 or 1220 rpm.

-From 1910 we know another Green engine, with 35 HP, on the Avro 534 "Baby" and Avro 560, but these were the Green 2-cylinder Vees, of which we do not have information at the moment.

-The triple Roe III was powered by another Green 2V.

-Later it appeared in V8, V12 and W18.

-The D-4 was a four-cylinder engine that gave 60 hp at 1,100 rpm. A 2.75 hp auxiliary unit appears in a Flight magazine of 1914.

“Green 2.75 hp”

-The E-6, is a water-cooled, six-cylinder intended for 120 hp at 1,250 rpm. There were also 6 cylinders with 100 and 150 HP.

“Two views for the 120 hp”

-The 120 hp Green engine was manufactured until 1916. Mirrles, Bickerton & Day also made these engines under license.

-Below we show a small eight-cylinder that gave 82 hp at 1,100 rpm. It is from the year 1914, and it had the same configuration as the 4 cylinders. (possibly they had the idea of coupling of two of these)

“Green 82 HP”

-As a logical advance towards current trends to obtain higher power, they produced liquid-cooled V-12 engines with powers between 275 and 300 hp.

-These engines had a very low max rotation, 1,200 rpm.

“Green V-12”

-Later the 450 hp engine appears with 18 cylinders in W. Below we see it from the rear.

“Green W-18”

From Appendix 6: Below we show new images of Green engines.

-They are built by Green's Motor Patents Syn. Ltd. in London.

-First we show the water-cooled, 30/35 hp engine with four upright inline cylinders.

-They had pistons with a bore of 105 mm and a stroke of 120 mm.

“Green 30/35 hp”

-The 50/60 HP had pistons with 140 mm of bore and 146 mm of stroke.

“Green, 50/60 HP”

-From this last engine we also have two pictures that appeared in 1911 in the English Flight aeronautical magazine, and that is still being published.

-They are two strictly side views, from the right and from the left.

“The Green 50 hp” (PiP)

“A Green engine on a Flanders monoplane”

From Appendix 10: We have a Green four-cylinder upright in line engine diagram to verify the proportions. It had perforated rods to save weight.

“Green 35 hp engine”