Thanks, guys. I agree that all of the last few technical suggestions are possible. Interestingly, the report was of audio alarms only. I specifically asked about voice warnings and apparently none were remembered as being heard. Overall this is definitely an interesting example of observation and memory being, perhaps, inconsistent with reality; limitations of homo sapiens I am afraid. It was actually my idea to air this on PPRuNe not my friend's, and curiosity was the only motivation of both of us. No-one wants to start stirring it unnecessarily with AA or the FAA.
Scroggs, how are you? Let he who is without sin cast the first stone! Did you bid for/get the trip that we discussed next month?
Best regards and thanks to all.
L