"to compare with our own Ordnance Survey maps"
Front Cover of a 1945 Ordnance Survey Map
Public DomainFront Cover of a 1945 Ordnance Survey Map - Credit: wikimedia commons

 Ordnance Survey maps are a series of detailed maps that together cover the whole of Britain, created for military purposes during the Napoleonic Wars. The popular Ordnance Survey ‘leisure maps’ are at one inch to the mile, showing small areas in detail. These are still available in traditional sheet-map form today. Larger scale maps at six-inches-to-the-mile or more were also created.

Ordnance Survey website

 

Part of a 1946 1-inch-to-the-mile Ordnance Survey map
Public DomainPart of a 1946 1-inch-to-the-mile Ordnance Survey map - Credit: Ordnance Survey