Try this one.
Just remember this is post war (only just) and what sounds like the sound file breaking down is reported to be the air passing through the supercharger being compressed and cooled to the point where the moisture in the air freezes and causes a misfire. I think it's prince of darkness (Lucas Electrics) causing the misfire but ill go with folklore as it sounds more interesting.
http://youtu.be/fZMPDCNyQxE