Lillingstone Dayrell ‘Geocaching’ facility.
If you look at http://www.geocaching.com and type in the Post code MK18 5AT it seems to be ‘alive’ still. Book Link. Link. Link. Link. Twitter.
http://en.wikipedia.org/wiki/Geocaching
http://shop.geocaching.com/default/3rd-edition-complete-idiot-s-guide-to-geocaching.html
http://www.geocaching.com/about/thebook.aspx
http://www.geocaching.com/about/history.aspx