I have just come across this statement from Bournemouth Council on the internet and thought I would pass it on just in case it has been passed by:
Unfortunately, following several problems on Council land at a range of parks and nature reserves as a result of geocaching, this activity is not permitted on Council land. Problems have related to the digging up of ground by treasure hunters, concerns raised by local users and residents, and insurance issues, particularly the issue of who would be responsible should there be an accident involving the organiser/geocacher and/or the public.
For more information, please e-mail Bournemouth Parks, or phone 01202 451629