7. O Little One Sweet - J.S. Bach
Although the main focus of my Top 10 carol selection is on English choral music, it would be impossible to leave Bach out of the list, such was his influence on the English church music canon. The vocal harmonies in this short carol are as close to musical perfection as anyone has ever come. The best recording I could find of it is in the original German - O Jesulein Suess. It's a little quiet so you may have to turn up the volume on your PCs.
I am dedicating this to my father-in-law, Neil Broome, who loves this kind of music and regularly gets the family to sing it round the piano at Christmas.