I may see myself writing my M.Litt. dissertation about this poem:
Westron wynde, when wilt thou blow,
The small raine down can raine.
Cryst, if my love were in my armes
And I in my bedde again!
Has no one broached the question of why this lyric poem (or something very much like it) became the musical basis of three different Mass settings in England, when matching secular lyrics with the Ordinary of the Mass (as in Missa Entre vous filles and Missa mille regretz) was clearly a Continental trend?
One caveat: St Andrews seems rather poor in library material on medieval and Renaissance music.