Tim has sent the following update: After several emails and a telephone call a member of the Gwynedd Archeological Trust has visited the site and I have been told by a member of CADW that they will be visiting the site this week and discussing matters with the owner.
They will not be able to give me more details - presumably legal action may be in the line.
Thank you for pointing me in the right direction.
Something is not right. This message is just to keep things from messing up down the road