Re-Visited 27.02.20
I summited Knockdolian many years ago but lost the photos so I had a good excuse for a second visit.
The short steep walk more than compensates the effort required with fantastic 360 degree views including Ailsa Craig to the NW.
Approaching Ballantrae from S, I crossed the Stinchar Bridge and turned right beside the old castle. After 3 miles on the B7044 there is a sign for the Knockdolian Hill path. It is possible to park beside a wood a quarter of a mile beyond this point. Retrace your steps and start the steep obvious ascent up a grass field leading onto a ridge towards the summit.
I was expecting a stonier cairn however the grass cairn at the summit looks like a natural knoll. There are no kerb stones, as noted in Canmore ID 62028 (go to Links), just a few rock outcrops.