Pembrey Gunnery Dome
It was certainly still there on Friday!
Try Google earth at N51 42 34.18 W004 18 22.35. It is now a listed Grade 2 building, nothing remains of the interior, it was used to house goats in the past. I think there are about 5 left in the country.
Work on the airfield recently revealed a Pickett-Hamilton fort as well.