This is the mounting box/swivel and wind vane for a small wind generator, originally a 12/24 volt device.
The box has a swivel mount in the base, designed to fit onto a pole. The swivel has electrical connections allowing the box to turn freely.
The vane is designed to keep the generator pointing into the wind.
Sadly the generator itself is no longer with us. I only have what is in the photo.
Collect from North Kendal