I have just added this to the map of places to fly your drone at Drone Scene:
Land owner permission requirements unknown.
To get here you need to exit the M4 at junction 40 and follow the signs for Goytre. Once you've passed through the village you should be on a narrow road through the forest. If coming from the South there will be a small lay-by on the left. Park here, cross the road and take the signposted path.(heading East). Lovely fl;at wooded walk with a gentle incline - stick to the main path and when the path splits you can take either but the more direct route is downhill. Not long after you will see a steep embankment and that is one end of the reservoir.
The originator declared that this location was not inside a Flight Restriction Zone at the time of being flown on 12/07/2020. It remains the responsibility of any pilot to check for any changes before flying at the same location.