The Ears Are Listening
This is old tech. Not really old tech. Just old tech. Pre radar. Pre World War II. In fact, these listening devices were developed during World War I to detect enemy aircraft approaching England.
These weird and wonderful half Death Star-like spheres used sound waves and microphones to detect German aircraft which gave the RAF planes just enough time to scramble and mount a defence.
Radar made these sound mirrors, aka listening ears, obsolete but they stand hidden in the remoteness of the Kent countryside as a reminder of the past.
The area has a desolate feel to it. In the background stands the Dungeness nuclear power station. Step out onto the sandy beach at Romney Sands and the tide can be a mile away with people making the most of the space to land surf.