Degree of tolerance 1807-1900

I ask if any original survey material is still extant in relation to an actual survey of xxxxxx, which might indicate the true line of the former boundary yard wall?  What degree of tolerance was permitted between actual survey details, in 1807-1900 when compiling the second edition Ordnance Survey Map, and how reliable might a boundary line depicted on the map be in relation to its true location on the ground?   

Thank you for your e-mail dated 8^th February 2010. I regret to inform you that Ordnance Survey is unable to help you with your enquiry as we do not hold this information.  Ordnance Survey does not depict property boundaries as such, but does record the existence of physical features within the limits of the specification.  Those features may or may not comprise property boundaries.  Ordnance Survey cannot resolve boundary disputes or determine property ownership.

Land Registry advises that any dispute concerning property boundaries or the extent of registered land should be brought to their attention at the earliest stage, to establish if they can assist in resolving the matter.  Where there is a debate about property extents, Ordnance Survey can and does undertake survey work at the request of Land Registry.

Ordnance Survey does not keep surveyors notes and there is no original survey material still in existence. Because of this we are unable to answer the basis upon which the 1901 25 inch map may have been prepared.

As for the degree of tolerance, the accuracy of scaling in the nineteenth century tended to have no formal processes. One of the only forms, was a maximum error of 1 in 500 when laying down chain lines (a chain is a unit of measurement equivalent to 22 yards) from one triangulation point (or ‘trig’ station which is a control point) to another usually 1.5km to 3km apart. This led to a maximum permissible error of three metres. The distances referred to on the map are a lot shorter and so should be more accurate, although no accuracy statements were created for distances this small at this time.

Please note that your enquiry has been processed to Freedom of Information guidelines. If you are unhappy with our response, you may raise an appeal to our Appeals Officer at:

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Ordnance Survey

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Thank you for your enquiry.

Reference number: FOI1038/February 2010