Mike
Thanks for your reply. It is interesting to hear you say that the pilot told you that he "was declaring an emergency". I have had to declare both MAYDAYs and PANs in the past. Luckily it was in the UK so I knew the correct phraseology. I have been seen radar replays of US aircraft in emergency situations in the UK and in my experience they have more often than not failed to use the accepted prefices.
The point that I think I am driving at (I think) is that I want to know what to say when it happens on your side of the pond (and thanks to your information, I think I have a good idea now), and similarly I hope I have given US operators to the UK some idea of what to do.
I know that in an emergency anything goes, but it is nice to get as much right as possible first time around, to avoid repeating things and thus giving more time for thought. I think that correct phraseology for your location fits into that model. Thanks again for your help.
G W-H