Ben - Pretty sure this is its first year. There is a thread already going with some detail:
http://www.runnersworld.co.uk/forum/forummessages.asp?dt=4&UTN=187420&last=1&V=8&SP=
I run some of the route most Sunday's, it is pretty wooded / estate / farm land lots of good forest trails. There will be some undulations but no real gradient. Should be an opportunity to post a quick time for those who want to.