TeaSea
SOH-CM-2014
Well I base my viewpoint on that of Miles staff, and more importantly that of Eric 'Winkle' Brown.
Eric was an RAE test pilot, flying a world record 487 types of aircraft in his career (not including variations - basic types only). That's as pilot in command, none of those were counted in the co-pilot seat. Generally regarded as the best test pilot who has ever lived. First ever carrier landing, most carrier landings in history etc etc. He led all high-speed tests with the Spitfire (and variable incidence wing) and was scheduled to be the chief pilot of the M52. I'll go with him!
I've no doubt from Brown's perspective, that this was true. With the cancellation of the Miles project, he along with his entire team would have immediately been isolated from receiving any additional engineering data from the US -- as they should have been on any classified project. That is a far cry however from claiming the US walked away from its agreements with the UK. Further, since much of the study on supersonic flight prior to the war came out of the US (in the 1920's no less), Browns assertion would ignore all that data being poured into the UK effort.
In any case, it is a shame that the Miles aircraft was never given an opportunity to be physically fly through the barrier. On that point I think we can all agree....but like I said, we do so looking backwards knowing history, and not peering forwards trying to guess what's most important.
I suppose from a long term view, it really didn't matter, except to aviation aficionado's like us.