This was a lot of effort with no reward I am afraid to report. I parked at the entrance to the private road to the farm and walked up the drive. This was then followed by a 'sneaky' walk across two fields and over a fence which took me to the bottom of the wooded hill where the Hillfort is. Despite scrambling up through dense undergrowth and spending about half hour looking, I couldn't see any sign of defences.
The fact it was raining didn't help either!
One not to bother.