The two slabs set in the passage wall.
As the passage is only 0.6m wide here, an ultrawide angle lens had to be used to for this photo, so it does show the classic distortion
produced by these optics. The inner western edge of the passage can be seen on the right with the edge set slab at its base, the
vertical slab is on the left, it barely protrudes from the masonry. Turner (3) reports that Burroughs found a rectangular recess in the walling
here, its location is shown by the purple outline above. The recess was 0.7m long, 0.3m high, and 0.4m deep, it has been filled in at some
time in the past so no trace remains today. Davidson and Henshall (6) suggest that the opening was merely the result of masonry falling out.