Just noticed today that underneath said problem, there is a block about the size of your average coping stone which looks as if it is 'wedged' underneath the block, holding it upright. It MUST be holding some of the weight of the block, as it appears to have a very clean split right down the middle of it which can only (to my eyes) have been caused by it being crushed from the block above. Check it out when your next there, unless you've already noticed it. scary stuff!
