The proms, BBC tv Advert

[MOORISHIDOL]

BBC 1 & 2 telivision, have been showing a short advert (between programmes) for the Proms.
The ad shows small black musical shaped notes drifting down from the sky, a bit like snow!
Does anyone know the piece of music that is playing, its istrumental (no voices) its classical, slow & quiet, its also an old piece, I used to hear it from time to time on the radio when I was a small child, too many years ago to remember.