The Color: This is a 2-color stripe alternating between Tintagel (a royal blue-purple) and Yvain (straw-colored golden-brown). A bold combination for utmost contrast.
The Name: Cadbury Castle is an actual location: an ancient hill fort in Somerset, England. It is one of the suggested locations for Camelot. Because it is located in the southern part of England, along with Tintagel which is traditionally the place of Arthur's conception, it would make sense for him to still be in that area and to have used this location for his own stronghold.