My friend and colleague, Chris Roth, has made lots of maps available in Visio, his latest being Germany ( http://www.visguy.com/2008/03/01/map-of-germany/ ). Well, we Brits hate being outdone by a German-American, so I have decided to make my UK Map shapes for Visio publicly available at http://cid-3350d61bc93733a9.skydrive.live.com/self.aspx/Blogs/UK%20Geography%20Structure.vsd .
I created the UK map several years ago by converting from PDF to SVG to Visio, and each of the counties and boroughs have a single rectangular Master, Admin Area. I used code to replace the rectangle geometry with the actual shape geometry. This means that, although they are all different, they actually have the same Master, thus making it easier to propagate any changes, such as Shape Data rows.