I think we must have been a few feet away as we were searching here we did find a Adit that only went in a few yards and also something looking very suspicious under the water line directly below it however we were about 50 yards further up than the farmhouse.
What we did notice on our walk up was some VERY old stone steps going down from the farmhouse to the waters edge, looking at your map i think this must be almost directly opposite the adit π
"I Dont Know Where I am Going, But When I Get There I will Know Where I am"