It's worth remembering Karl, that G-SPIT/ MV268 is actually MV293, so shouldn't really be used as a basis on which to model one of Johnson's aircraft.
View attachment 546253MV293
Same aeroplane.
Also, just to confuse, MV266 was a high back XIV (EB*J, flown by Sqn Ldr John Shepard, OC 41 Sqn).