[Crumpp]

Because IMO in combat area easily a damaged plane would be taken down by the enemy...

That is correct. A bent airframe is not good. The plane is hard to control and weakenend.

I ask because of the possibility of not investigated accidents regarding structural failure

There were plenty of uninvestigated accidents. In wartime, they would be chaulked up to the enemy. Common sense tells us that wings coming off in a dogfight would be chaulked up to enemy fire or pilot suddenly breaking out of a turn to wings level was hit.

There would be no way to resurect the dead or examine the wreckage to discover the airframe was broken during a flick maneuver or bent in a hard turn above Va.

Facts are we will never be able to quantify that statistic. None of this changes the defined and measured characteristics of the aircraft nor does it invalidate the Operating Note warnings.

Where does he say only Mk 1 and II's?

The issue was solved in the Spitfire Mk V!!

You understand that the bob-weights and subsequent empennage changes to the design were to fix the instability??

It is only a factor in the early Mark Spitfires.

Aerodynamically, the instability is a very easy fix. The only reason it was not solved much earlier is the fact the Air Ministry had no defined standards for stability and control. Without measureable standards, the pilot stories of "easy to fly" simply overshadowed the few engineers who knew better.