Our daughter lives in Caerphilly and we are regular visitors. She regularly walks her dog in the forest, knows the cache location and is available for any urgent maintenance.
The Headline coordinates will take you to the Car Park of Fforest Fawr.
Fforest Fawr is a mixed woodland with several trails to explore as well as the famous carvings, the Three Bears' Cave and Castle Coch.
To find the coordinates for the cache, which is just off one of the many paths, you will need to solve this puzzle.
IS WM SM UM ZE IW EUT MO VT JT HT SA OM SI
You can validate your puzzle solution with certitude.