AA, I am wary of stepping on anyones toes here, I do not think it is for me to present the facts known about STF, some facts are still being teased out. My own background is no secret and I have some knowledge about how trials equipment can appear on aircraft. I was serving on a specialist section when our fleet lead aircraft was destroyed in the Kosovo war.
Given that the pilots were SF-trained and the kit was originally intended for such people, there are different methods and routes as to how that trials equipment might have been;
a Purchased,
b Fitted,
which are not necessarily "mainstream". With the MoD teams responsible having no experience whatsoever in the implementation of airworthiness, treating it as an unnecessary evil.
As for POSSIBLE breaches of the regs, it is probably safe to start from the generally accepted baseline that the Mk2 was not airworthy at the time (as described by John Blakeley). It is highly unlikely that, against that baseline, a SM/STF installation was implemented iaw the regs because it is one very obvious area where MoD don't adhere to their own regs. (See Nimrod evidence, for more recent breaches).
Regarding the delayed response from Des Browne. Could the reason for the delay be because Government and MoD has realised the implications of “allowing” an “appeal” which is largely based on airworthiness issues. A “result” on any one of those would re-enforce the position on Nimrod and demonstrate wider and longer term failures by MoD, and stop it claiming Nimrod was a one-off?
MoD suddenly looks very weak and vulnerable on airworthiness issues.