Perhaps you've noticed the preponderence of Welsh words with no "vowels" in it, but with a w instead. Most people mistakenly believe that this, being a w, is a consonant. However, it is not only a consonant, but also a vowel.

In Welsh, there are two uses of w. The first is that of a consonant: "gwyn" (white) pronounced "GWIN." As is pointed out above, "GWIN" is really pronounced "GOOIN," with the "OO" being said rather quickly, as opposed to the second use, which is a vowel: "cwn" (hound) prounounced "COON"--here the "OO" sound is drawn out and made a vowel in its own right.

Why do the Welsh write like this? Well, it goes back to the Greek. In Greek, a long "O" is an omega: Ω , which the lowercase is written: ω --rather like a w, isn't it? It is also interesting to note that in some manuscripts like the Red Book of Hergest and the Book of Taliesin, there are two forms of what we write as a w: the first is rather like a v with a line over it: 6 (as an aproximation). The other looks like two l's and a z: llz (being a very bad aproximation). The first represents a vowel, the second a consonant.

It should come as no surprise that the Greek alphabet could have a direct influence on Welsh writing, without the intermediating of Latin; it is said by Julius Caesar that the Celts wrote using the Greek alphabet (ogham was only for monuments). Greek manuscripts are said to have come to Ireland before and after the fall of Rome, and there was a good deal of comings and goings between Ireland and Britain during the late-Empire, early-medieval period, particularly with monks.