Friday 2 March 2012

Finding Your Highland Titles Glencoe Estates Plot

Highland Titles claim you can find your plot of land just by using an Ordnance Survey map. Like a lot of the information given by Higland Titles, this does not I think bear close scrutiny. Quite simply, Ordnance Survey maps, good as they are, are not accurate enough to be able to accurately locate a square foot of ground, this can be demonstrated using accuracy figures from Ordnance Survey themselves.

Scale and method of original survey



Expected Relative Accuracy at differing confidence levels




68%




95%




99%
1:1250 scale Maps surveyed at 1:1250 scale using instrumental methods to provide a framework of controlling detail.



±0.4m




±0.8m




±1.0m
1:2500 scale resurvey/ reformed Maps surveyed at 1:2500 scale using instrumental methods to provide a framework of controlling detail.



±0.9m




±1.8m




±2.3m
1:2500 scale overhaul Maps originally recompiled from pre-1946 County Series mapping.



±1.2m




±2.3m




±3.0m
1:10,000 scale * Maps surveyed at 1:10000 scale using instrumental methods to provide a framework of controlling detail.



±3.5m




±6.7m




±8.8m

* Some generalisation of detail does occur for cartographic reasons on 1:10,000 mapping therefore some points of detail may appear to be less accurate than these standards.

The large scale 1:1250 scale map can only produce an accuracy of plus or minus 1 metre at 99% confidence level. The best 1:2500 scale map can only produce accuracy of plus or minus 2.3 metres at 99% confidence level. I would say it is not therefore possible to locate a 1 square foot plot using an Ordnance Survey map.

The Keeper of the Registers of Scotland seems to agree that the land cannot be found using an Ordnance Survey Map. “The Keeper of the Registers of Scotland cannot accept applications for registration in the land register for land not sufficiently described to allow it to be identified on the Ordnance Survey Map.”

How about GPS, surely that would locate a plot? Again when we examine the accuracy of commercially available GPS systems we find that the accuracy is not sufficient. Garmin, a very respected manufacturer of GPS receivers claim an accuracy of 15 metres on average. "Certain atmospheric factors and other sources of error can affect the accuracy of GPS receivers. Garmin® GPS receivers are accurate to within 15 meters on average."(http://www8.garmin.com/aboutGPS/). Not accurate enough to positively locate a square foot of ground then.

I have no idea how you could possibly locate your square foot of ground, if anybody does please get in touch and let me know, I'd be very interested to find out, and will correct this post if it is a valid method.

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