Mark J. Reed wrote:
> But whence the English name "wye"?

It must derive from Old English [y:], since the letter was used that 
way. As late Latin was also psilotic (i.e. they dropped their aitches) 
that would've been the contemporary Latin form also.

Of course, Old English /y(:)/ became /i(:)/ in Middle English, but that 
would've meant that I and Y had identical names! Presumably when the 
vowel was unrounded, the letter name retained initial lip-rounding, i.e. 
became [wi:], hence modern English [waj].

It did occur to me that there might have been dialect forms with initial 
non-phonemic glide in Old English, i.e. [Hy:], which would presumably 
have given Middle English [wi:].

"Ein Kopf, der auf seine eigene Kosten denkt,
wird immer Eingriffe in die Sprache thun."
[J.G. Hamann, 1760]
"A mind that thinks at its own expense
will always interfere with language".