The Auxiliary Units were to be Britains own resistance should a German invasion have been successful.
Their existance was top secret and only acknowledged by the government in the 1990s.
Little remains of this local “OB” or Operational Base except a few depressions in the ground which become covered in wild garlic most of the year,
There is an excellent diagram by David Waller that lets you relate to what’s still visible.
Its most easily located by walking to the end of the promentary above where two stream meet.