Hello Rob,
Very interesting your information over the Deerhound aero engine from Armstrong Siddeley.
Armstrong Siddeley was a company for production of luxury motor cars and aircraft engines.
Logo:
Deerhound engine variants:
Deerhound I – 1,115 hp (831 kW): four built.
Deerhound II – 1,500 hp (1,118 kW), capacity enlarged to 41 L (2,509 cu in) by increasing bore and stroke: six built.
Deerhound III – 1,800 hp (1,342 kW), major redesign by Stewart Tresilian: one engine built.
Best regards
Joerg and Yoki