Well that was the trials result as reported.. ..maybe they used squadron aircraft rather than R-R factory specials?
& Spit XII was never any kind of real match for the Typhoon, hence ~100 built vs 3,300..
Service pilots also ran impromptu speed contests,
& sure W, you are correct - that brute Sabre power could see off any single-speed supercharged RAF Spit..
Beamont, as Hawker test-pilot was charged with full-out flying to help determine the 'tail gone' issue..
..including Mach crit dives & max G pull- outs.. ..according to his memoirs..
& wee Brown went a bit quicker in the Tempest didn't he - Mach 0.87, wasn't it?
Not that the Spit test value margin - was of any practicable use in combat anyhow..
& gravity is pretty weak, diving is a deliberate, precise action, & it is power & aero that counts..
Spitfires were mostly modestly powered & fairly draggy, the P-51 was much slicker, they could even
out-dive the more powerful Griffon Spits, even if those weighed more than Merlin Spits..
Dr Moreau sez..
"Who breaks the law... goes back to the House of Pain!"