:Whoops!  I just rechecked the map more carefully, and the UK is the same as Western Europe, but the color code specifies 230V 50Hz.  I think this discrepancy may have to do with EU harmonization of electricity, which relatively recently designated 240V as the common standard.  Don't know how easy it is to change the map without going back to the image source.  Perhaps a textual note can be added in the meantime?