To get there; come off the M25 at Junction 18, from either direction at traffic lights at the top of the slip road take the A404 towards Rickmansworth, follow this road for about a mile and a half. At the first roundabout take the first exit, downhill for 500 yards at the next roundabout take the exit almost in front of you. The entrance is less than a hundred yards on your left from the roundabout and quite difficult to spot so be careful, there is a small sign on the lamppost on the right hand side of the road. If you start going up hill on the small dual carriageway you've gone too far, so go to the top of the hill and go around the roundabout at the top and come back down, remembering the entrance is now on your right.
View with Google Maps