Understanding publication dates
It can be difficult to grasp how all the historical maps available through Historic Digimap relate to one another. The publishing date ranges of each Map Series overlap, meaning that there is not a clear sequential flow from one map series edition to the next.
This is especially true for map editions in the post World War II National resurvey to the National Grid. As the whole of Great Britain was being re-surveyed, those areas surveyed first were being resurveyed and resurveyed again for revised maps well before more “remote” areas of the country were surveyed for a first edition National Grid map.
So whereas one location may by 1975 have a first and second edition National Grid map, a second location may still only have a pre World War II County Series map.
The relationship between the Map Series is further confused by the way Landmark Information Group (which digitised the paper historical maps) organised the maps into temporal layers called “Epochs”. Although these “Epoch” layers are useful in terms of using the historical map data in a Geographical Information System, they do not always relate directly to a specific Map Series (again, this is especially true for post World War II National Grid Mapping).
The “timeline” diagrams available here have been created to help you visualise the temporal relationship between the Landmark Epochs and the Map Series and Editions they contain.
Time line of publishing date ranges for all map series, in all Landmark Epochs
Time line of publishing date ranges for post World War II National Grid Mapping (Landmark Epochs 5-9)
Time line of Landmark Epochs for 1:10,000/1:10,560 scale National Grid mapping
This timeline compares 1:10,000/1:10,560 scale National Grid mapping with that for actual publication of 1:10,000/1:10,560 scale National Grid map editions.