Someone would steal it [they keep taking the grave marker as it is]
Who would pay for it anyway?
The cost has not come up for consideration at this stage, just trying to get a feel for how it would go down. His grave markers getting lifted, was probably by some teenagers, thinking they could sell it on ebay, or maybe they have one each in their bedroom, to show off to their friends, or maybe the most viable reason, is that those in care of the cemetary are removing it, to cut down on the number of visitors, who arrive to pay respects to him (just like they tried to control who was allowed to attend at his burial),,,,but a monument would hardly be cut from the plinth, it would require a lot more effort, I do see it would need some form of protection though perhaps a railings or something.
