These Caches exist, but the cache page may have been archived by Grounded Inc. For an explanation see Robin & June's Geocaching Page
The "Burnham Beeches" Geocache is strategically placed, just a few minutes stagger from "The Stag" Public House 
on the edge of this mile-across nature reserve off the A355 north of Slough. June's Dad, Jack Ponsford, featured on our Sunninghill page helped me plant it, one extended lunch break. Jack says he remembers cycling past this area, as a boy 70 years ago, and stopping at "The Green Man" for bread, cheese and a pint of shandy :-) The car park opposite "The Stag" pub is open from 0800 in the morning until after midnight - no doubt at the request of the landlord.
The impressive looking sign says that further information on this area is on +44(0)1753 647358 in (UK) office hours, and +44(0)1372 279488 for emergencies. The all-important location of the pub car park is N 51° 33.014' W 000° 37.651'
You should not have any problem finding this geocache quickly. Just follow the paths, avoiding the mud, enjoying the ancient woodland, and keeping a lookout for wild boar. I cannot imagine any other reason for there being what appears to be a pig sty in a rather nice little spot. Or maybe it was low cost overnight accomodation for those who got locked in the car park ? This is the usual Lovelock Geoacache, holding disposable camera for you to take a picture then return to the cache, toys and books for children, and lots of other low cost "goodies".
If you wish to contact Robin, and want a reply, please email him direct on gpss@compuserve.com He regrets that he does not have the time to reply indirectly through geocaching.com email.