For interest's sake, here's a series of pictures of the 1974 wargame http://www.wargaming.co/books/paddysprawling/articles/sealion.htm (I had NEVER seen a single wargamer wearing a tie). I own a copy of Cox's book, found it second-hand years ago, it was what got me into alternate history. An enjoyable read, if you can get a copy, with some useful tables at the back. I also own Britain Stands Alone http://www.gmtgames.com/p-255-britain-stands-alone.aspx and have gamed Sealion a few times. From memory, I don't think the invaders were ever successful. For the Germans, it's always "I have so much land power, but I can't get it to Britain". This game showed me that Sealion wasn't going to work. You can't resupply AND reinforce AND expand the bridgehead fast enough. Even when I took out the naval aspect (Why yes, every RN ship simultaneously broke down), the ports in the invasion zone were captured damaged and kept that way by the RAF. Then the October storms arrived and the supply chain was cut.