Funfly you asked
As a passenger, if we are at 40,000ft and loose pressure then I am going to die?
Answer no as long as the crew start a descent fairly quickly. The BAC 111 did not have oxygen masks (except some delivered to the American Airlines.) They could cruise at up to FL350 and in the event of a rapid decompression you had to get down quickly to keep the passengers conscious. While being trained on another aircraft I remember being taught that above about FL380 if there was a rapid decompression and you did not have a mask and the plane did not descend you would be unconscious after about 30 seconds and brain damaged after 2 minutes.