Digital Images Archive
175. One-inch Third Edition (Large Sheet Series) sheet 135, with military grid (CCS 218B/52/2)
This is one of a few one-inch sheets overprinted during the First World War. This sheet is overprinted in red with a 2000-yard alpha-numeric squaring system, with 400-yard subdivisions numbered 1 to 25. Part of the overprint cancels the two-inch blocks in the border of the map. The system is parallel to the sheet lines of the map, with the square 9A in the north-west corner. The function of this grid has yet to be explained.
From a copy now in the Map Department, Cambridge University Library.