If using the Gwynedd guidebook from CADW and Frances Lynch, the stone stile referred to is blocked off. Access is to the left rear of the house through a gate: given it's private land, do check first, as landowner was enthusiastic to point out it's private property, but did point in the right direction when showing the guidebook and professing interest in such places.
Something is not right. This message is just to keep things from messing up down the road