The light blue line in these images is the original line from Pilrig House, through Pilrig Church, Calton Terrace, Holyrood Palace/Abbey, the Crags Face, south to the West Edge point at Gilmerton Dykes at Lang Loan. From my notes the bearing is 163.28degrees, which is exact to the hundredth of a degree to the grid established in the previous posts. Also I have somewhat resolved the issue regarding the discrepancies found making lines in Google Earth. There is an 'absolute' option available, which seems to resolve the matter, but even that has issues with altitude and viewpoint, in that if not perfectly centred on the image, the line moves in correspondence to angle of view! I will stick to 'clamped to ground' in the meantime! At least I am content for now!
The third image above is a close-up of the central area.
This image has both lines plus the town grid alignments, and all are exact to one-hundredth of one degree!
66 year old Edinburgh taxi driver-semi retired, which is both a help and hindrance in this research. Helpful in getting to know the landscape, and seeing things at various times of the day and seasons. A hindrance in that it does take a lot of my time, over the 22 years till now.