The Charles Close Society for the study of Ordnance Survey maps
Digital Images Archive
1:1M of Great Britain with overprint showing catchment areas
The base map is Sheet 2 of the 1:1M in the style of the International Map of the World (Hellyer, Indexes, 104A2). It shows catchment areas as defined under the 1930 Land Drainage Act. It had long been apparent that the multitude of small drainage authorities would be more cost-effective if they would combine their efforts to improve the main rivers into which their systems drained or were pumped, but hitherto there had been no statutory mechanism for this. The Act enabled River Boards to be set up within England & Wales which could define catchment areas within which they would exercise their powers. The Ordnance Survey marked these catchment areas on the six-inch. This 1:1M provides a useful overview at the date of the map - changes continued to occur as new statutory orders were made.
The bottom half of the map is missing, along with the date, but it is thought to be about 1937.
From a copy donated to the CCS which is to be lodged at Cambridge.