Wheatley was initially buried at Duffelward Civil Cemetery before being moved to Reichswald in April 1947. There is a detailed description of him being shot down, by a Bf109 E-1 fitted with only 4 x 7.9 mm machine guns, allowing him to reach 10,500 metres and effect an interception. Aircraft crashed in at Herwen, Dutch territory (at that time) but Wheatley landed near Duffelward on the German side of the Rhine, when his parachute failed to deploy. Spitfire PR IB N3069 near Herwen. One interesting aspect is that it was reported to have been painted in a mint green camouflage, presumably thought better for high altitude work. https://www.facebook.com/pg/SpitfireN3069/about/
Those test dives at RAE were properly instrumented, but figters were tidied up, e.g. Spit 21 had guns and gun blisters removed. Highest Mach Number for it was .88 and for Spit PR XI .91. These figures are from Royal Aircraft Establishment at war by Richard Dennis (2008). Full details of the tests can be found from Review of high speed flight research at RAE. W A Mair. RAE report Aero 2152 Sept 1946. Have not seen it but according to one writer the Spit 21 carried a pitot comb 14" wide. The Mach .96 dive over South China Sea on the other hand is based on normal Instruments and meteorological data. The XIX was on meteo flight IIRC. I have read an article of it from an old Aeroplane Monthly, author was IIRC Alfred Price but I'm still sceptical on it. But the table and the graphs shows the data on which the claim is based. These are probably from the AM article mentioned.
