Can't resist to add my piece to this imbroglio.
In old Roman inscriptions there is no letter "U", but "V" stands for the U- and V-sounds indiscriminately (there is no "W" either, of course).
And as I learnt it, the English pronounciation of "w", e.g. in well, is sort of a "consonantized u", so this would indicate that Romans also pronounced their "V" in this way in certain positions before vowels.