That sinking feeling

We seem to be experiencing a spate of sinkholes suddenly appearing in places around the UK.  They are the result of caves collapsing as the rock that support their roofs is undermined by erosion.  They have appeared several times on the news and there has been an explanation of their formation by a geologist from the BGS.  The rise in groundwater levels caused by the recent heavy rains combined with geological vulnerability of certain rocks (chalk and gypsum are particularly vulnerable) make these hazards sudden and unpredictable.  Security camera footage from the National Corvette Museum in the US shows a hole forming.

The Vale of Glamorgan does suffer from sinkholes as well because our bedrock geology here is mostly limestone.  How solid is the ground under your feet?