thank you, Brian, that's wonderful; you've done a huge amount of work on my behalf
It is interesting that Arthur Haqg of Napier (ex-de Havilland) was said to be an expert in low-drag ducting of engine cooling and induction air, and he did much of the design work on the racer (along with George Cornwall of Heston). The airplane was Hagg's idea, originally--the thought of building something tiny and superlight around the Sabre. So whether he profited from Meredith's workor was proceeding in parallel we'll probably never know.
You've also reminded me that the P-51's magical ductwork didn't so much add speed to the airplane, at least at first, as it did reduce net cooling drag.