Hello WTRFPSU
The lower part of the Shrine rides right over the water tank shown as a covered reservoir on detailed mapping of the area . Deffo not a secret bunker or Jimbo's HQ!
Not teccy enough to post the map up here but can be found on the County council Rights of Way website mapping GlosMAP http://prow.gloucestershire.gov.uk/website/ppp/viewer.htm
Agree with dobiejessmo regarding litter. seeing as it is a scheduled site and we are a a bit cheeky riding on it, digging and littering does not do us riders any favours.
STS