Thanks Turin. I thought perhaps that i'd had too much of the excellent BA Chardonnay on my flights, and it was the old ears playing up!
I think with a comment like that it's more likely for your tastebuds to be playing up!
Wing Fences/Lets:
Winglet: 747-400/MD-11/A330/A340
Wing Fence: A300/A310/A320Family/A380
Basically, in appearance terms, the wing fence extends to an equal distance below the wing as well as above.
Don't know jack about the aerodynamics, but it's something to do with vortices.....