Here is part of the 1 : 253,440-scale (that is, a quarter of an inch to a mile) Ordnance Survey map for the English Midlands. The map bears the following dating information:
First published by the Director General at the
ORDNANCE SURVEY OFFICE, CHESSINGTON, 1946.
Revision. Full 1915 with later Corrections.
The part of the map I've reproduced here shows south central Northamptonshire and some fragments of neighboring counties: Leicestershire, Warwickshire, Buckinghamshire, Oxfordshire, Bedfordshire, and Huntingdonshire. The area represented is a square about 34 miles on each side.
I have divided my map into nine sections for viewing. To view a section in detail, click on the appropriate thumbnail here.