@shortcolin There's a great article at
https://boghall-radio-masts.blogspot.com/ It says
The antenna was a Riometer (Relative Ionospheric Opacity Meter) ... The wires formed one plane of a corner reflector, the other plane was formed by the sloping terrain.
The centreline of the antenna was directed at the north celestial pole, so the antenna received radiation from the same area as the earth rotated .
It wasn't used for any military or HF communication applications.
So you were right on that.