Easy Street
While I agree with the vast majority of what you say, I think you are too kind to DE&S. After all, they are just a rebrigaded DPA and DLO, and MoD(PE)/AMSO before, with the same people (or their acolytes) in charge.
The SI report has many recommendations pointing to abject failures on DE&S's part (and their predecessors). It doesn't spell them out or explain the background, but that is the way of SIs. But ANY civilian engineer in DE&S with more than 5 years service should know;
a. Backwards, the procedural Defence Standard that, if implemented, would have prevented these failures, and that,
b. It was canceled without replacement about 5 years ago.
Every MoD Technical Agency was issued with his/her own copy of both books, for permanent retention. Still got mine. It is THE bible. If you take the engineering recommendations of the SI, I can point you to the section in the Def Stan that covers it, and is mandated.
That is a top level system failure and any investigation should uncover this fact very quickly, especially as it was a major factor in Nimrod, Chinook, Sea King, Tornado, Hercules etc etc. It is the recurring nature of this failure that should disturb everyone.
Haddon-Cave rightly reported the failure was implementation. The MAA is concentrating on re-writing the regulations. The SI report is all about failure to implement perfectly good regulations. That indicates a system that is not fit for purpose.
I've deliberately avoided mentioning the aircrew and leaders of the Red Arrows. Many excellent posts above say it all.