Fine this is really up my ally... The letter W , when pronunced as per Phoenitics is voiced bilabial-velar sound.
In Latin,
U represented a
W sound, which could only occur before a vowel. Consider
equus, “horse,” pronounced like [
ek-woos ]. You see that literal double
U, that
UU, and how it is associated with our
W sound?
While the
W disappeared from much of Latin pronunciation as it evolved into the
Roman languages, one influential variety of French,
Norman French, did have a
W sound, especially as a result of the Germanic words that flooded the language from Viking incursions into northern France. And Germanic languages love a
W. So, Norman French used a double
U to represent
W sounds in words.