I was also taught "sometimes y and w." That was what prompted my original post - I never could see w as a vowel. (I never thought of the Welsh usage - translations from other languages lead to some awkward constructs. Anyone ever figure out how Xristoul Colon ended up as Christopher Columbus?)

Of course there are the Latin vowels j and v, or is that the Latin consonants i and u? Distinguishing between i/j or u/v didn't happen until about 900 AD (I think - help me here some classical scholar.)