Probably very old news but I found these images quite helpful for 13pdr details. Don't watch the video linked last if easily offended by military PR, though.
http://upload.wikimedia.org/wikipedia/commons/d/dd/Trooping_the_Colour_2009_030.jpg
http://upload.wikimedia.org/wikipedia/commons/5/54/Trooping_the_Colour_2009_031.jpg
http://upload.wikimedia.org/wikipedia/commons/9/99/Trooping_the_Colour_2009_032.jpg
http://upload.wikimedia.org/wikipedia/commons/7/7a/Trooping_the_Colour_2009_033.jpg
http://upload.wikimedia.org/wikipedia/commons/f/f5/Trooping_the_Colour_2009_034.jpg
http://upload.wikimedia.org/wikipedia/commons/6/60/Trooping_the_Colour_2009_035.jpg
http://upload.wikimedia.org/wikipedia/commons/a/a9/Trooping_the_Colour_2009_036.jpg
http://cache2.asset-cache.net/xc/71182674.jpg?v=1&c=IWSAsset&k=2&d=77BFBA49EF878921F7C3FC3F69D929FD532E13667A0AF87BAE5D259229022E864CE0AA16D8937538B01E70F2B3269972
http://www.flickr.com/photos/guyzphotos/4956632338/
http://www.army.mod.uk/artillery/units/kings_troop/default.aspx
