I have been buying Clarks for some time; my last purchase before the Desert Boot was the Traditional Wallabee about 6 or 7 years ago.  The Desert Boot is a nice looking, comfortable shoe.  I usually wear a 12 or 13 in most shoes.  My Clarks Wallabees are a 13 and are just a touch large but I recall that the 12 was just a little too small so I followed suit when I ordered the Desert Boot thinking that Clarks sizing would be consistent within their products.  The Desert boot is at least a half size larger fitting than the Wallabee.  With thicker socks it is not a problem but with dress socks they are too big.  I would have ordered the 12 in retrospect.  The crepe sole is so prone to discolouration that just wearing them around my office that was re-carpeted about 3 weeks ago for one day left them with enough darkness on the sole that I didn't think I could exchange them without incurring a restocking fee. Order a half size to whole size smaller than you normally wear and you will probably result in a better fit.