It would be too long and boring to go into depth here, but:
Dealing with DP Davies' quote: it is true that AT TIMES certification and development were going on side by side. Read no more into the comment than that - don't forget that this is still true for any type which operates outside the current norms. As an example, take the 777: ETOPS on service entry - the certification requirements for ETOPS on entry were being developed at the same time as the aircraft and while it was being certificated. Also, don't forget what happened when the GE90 proved incapable of passing the 'blade off' test.
The 747 didn't have manual reversion on the flt controls and the certification requirements would have been changed to reflect this.
This type of refining of the requirements while types are under development is common to the point of normality - concorde was no exception.
The quotes are largely paraphrased in order to make the book accessible to a wider audience and a certain amount of reading between the lines is required.
In terms of performance margins, TSS reqs exceed equivalent BCARs or whatever, and manoeuvre margins hugely so.I believe this is also noted in the same book. There are many areas where TSS is more restrictive, which should demonstrate that there was no conspiracy to fudge the requirements.
The numbers emphatically are not fudged, and the fact remains that SSC has larger performance margins than subsonic long-haul aircraft.
If only the man himself was still here to give us the whole chapter and verse.
PS TSS is not a secret document - it is available in the public domain for perusal. Unfortunately the only hard copy I know of is owned by BA and is NOT available to the public!