Silly question - if AH thought there was a problem with the altimeter or ASI could he have made adjustments mentally. ie if he believed it was under reading by a few hundred feet, made a mental adjustment to compensate.
Only asking as there appears to be no questioning any other pilot that had flown the aircraft in the last 2-3 months as to whether they had experienced malfunctions or had tech issues with the aircraft and if so had they reported them to the maintenance company either verbally or in writing.
Only because say for the last flight AH had undertaken in BXFI the altimeter had been under reading by 500ft or so and had now been 'fixed' but nothing recorded AH may have added the extra to compensate. Which would mean he thought he had reached the min gate height.
Also, how easy is it for a Hunter pilot to tell if the throttle is not performing at full thrust. Could AH easily tell by the feel/sound and speed at the time without even looking at the instruments.
I agree the maintenance companies since 2010 need questioning more and a more in depth audit of them is required, I doubt very much that any of them have qualified aircraft personnel working for them. My understanding of the historic jet society is most of it is undertaken by aircraft enthusiasts with little or no aircraft back-grounds.