Something short was required. Preferably not more than four letters to make it easier to shuffle bits of plastic around. Something that said Wales without explaining. Using the prefix Y is always a winner. It translates (according to my book on such things) as the peak. Saying it will cause confusion though. A VAN as in what is a Transit? And a long A sound. The lettering was from a set of Scandinavian shop signs, and the rest is bits of plastic sheet and strip. Valleys running in boards are not known for their ornamentation - something simple and concise is what's required.