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OS Positional Accuracy Improvement

Ordnance Survey large-scale mapping is affected by the OS’s Positional Accuracy Programme. Positional Accuracy Improvement will correct errors in the position of map features by altering their position relative to the National Grid. This will particularly affect GIS and CAD users who have digitised their own data over OS base data.

This means some digital map data will no longer appear correctly positioned relative to Land-Line or MasterMap Topography mapping. See the pages at the Ordnance Survey website for more details.