@Mark_Pilkington ;-

     Although the Q30 & Q70 etc were designed during the war, they didn’t hit the market until after the war, so for your purposes – there is an absolutely clear line in the sand there. Also, the Q30 & Q70 etc, whilst sharing a basic layout with the QII – and indeed – sharing exactly the same engine mounting points, these engine were a whole new design – no commonality whatsoever. Heavier, more robust, and with much more facilities to run accessories. However – all they actually shared were a few nuts and washers.

Back to the pre-war engines ;-

• The Gipsy Six Series I was the Fixed-Pitch original engine, with a tapered crankshaft end. I think this came out in late 1933/early 1934. The militarised version of the Series I was the Gipsy Queen III. These normally had the SI’s raised ‘GIPSY SIX’ lettering on the top cover deleted. Extra crankcase reinforcement by means of added through-bolts, and some later versions of the QIII used the QII top-cover, so as to be able to run more accessories.
• The Gipsy Six Series II was quite different to the SI. It had the No.1SBAC splined end to the crankshaft to take the DH PD30 VP airscrew. It also had different heads, pistons, barells, crankcase and camshaft. The militarised version of the Gipsy Six Series II was the Queen II. This also had the crankcase reinforcement and the ‘GIPSY SIX’ normally deleted from the top-cover.
• All the above shared oil filters and pumps, fuel pumps, carburettors and ignition system – and starters when fitted.

     Broadly-speaking, production of the QIII & QII were driven by production of the Rapide/Dominie*** and the Proctor respectively. All marks of Proctor Mk’s I – to IV were driven by QII fitted with a PD30, with the exception of some early MkI’s that probably had SII’s fitted.

I don’t know much about the Rapide/Dominies, but just to confuse things, Impressed Rapides were referred to as Dominies – as well as the actual military production.

The prototype Proctor MkI, serial number P5998, first flew on 8 October 1939 from Luton Airport, and the type was put into production for the RAF and Fleet Air Arm.

     I always used to presume that Queen III & Queen II production was all wartime. However, I now strongly suspect that they were ordered and went into production during the re-armament rush in the late 1930’s – in order to be able to be ready in time for the war. Some more research is clearly needed to clarify dates when production commenced. As I mentioned previously, there was full production data available on CD’s a few years ago.

*** ;-    A few Dominies  ( DH89A – Series Four I think….) were – and still are, fitted with QII & PD30’s – (A rather a pointless added complexity & weight for an a/c with a relatively narrow speed-range.).