JFZ,
I too can't log on to the article. I would like to read it.
As PN says, I do recall some of the old bold 51 Sqn types talking about the early Comet having to fly at low cabin pressure.
Re AD of which I have a little peripheral knowledge. There was always a debate about the limits for Air Despatch and para that some did not understand. This was when we had the Interim system which gave a constant flow of 5 litres pm. the paras then got a demand system with a simplex regulator built into the mask. This was cleared to 18K in UK I do believe the US operated it much higher. I met a guy in YPG who claimed to have used it at 35K. (I think this was BS as I am not sure what consideration was given to the crew).
In about 1999 we got to 25K with a duplex Carleton regulator. The crew had the old 317A Harrier surplus since the aircraft system was no good for pre breathing. Meggitt then produced a new regulator based on the 417 that had a duplex 100% arrangement but no air mix. this was tested higher but RTS was only granted to 25K. The Docs at Farnborough were listened to. I think this was a sound decision.
I note from the A400M propaganda they are looking at 35K for AD (I hope they are not reliant on the OBOGs which does not filter out the Argon). the latest system we had on the 130 had the intermediate pressure set at 350psi to match the ring main on the A400M. We were quite forward thinking as A400M was probably 10 years away.
There was quite a few in the wider community who just did not have a clue about the effects of altitude.
It's some time since I lost touch.