Not all metal detectorists agree that they should keep well away from such monuments. Like this bunch for whom a stone circle acted as a magnet:

"Mr Wood and other members of the Muddy Boots Metal Detector Club had been permitted onto private land near the Rollright Stones, an ancient formation of Stone and Bronze Age megaliths near the village of Long Compton. [...] close to the King’s Stone on March 28, the London-based IT professional found a well preserved skeleton, believed to be a Saxon woman dating back to about 600 AD".

Read more: http://www.banburyguardian.co.uk/news/metal-detector-enthusiast-unearths-1400-year-old-saxon-skeleton-1-6890831#ixzz3rqC0XgZ8

I think the way artefact hunting is presented to te general public is a matter of concern. Especially when there are no end of websites and blogs which deliberately present a wholly one-sided picture of the activity, maybe "Sanctuary' has come across any of the latter. What is so frightful about airing both sides of a discussion?