Dating ordnance survey maps
Some print codes towards the end of this era have an extra part tacked on the end, e.g. 20,000/1/43 R, for example, indicates 20,000 copies, printed in January 1943 at printing company code R (Robinsons).
c.1945 - c.1947: Each printing was given a print code, in an identical format to that used immediately pre-war.
These include maps used by the Ordnance Survey itself, a government agency since the late 18th century.
Some maps are ordinary editions but others are special editions or special printings. Although the first Ordnance Survey map was published in 1801, it was many years before it produced detailed maps of the whole country.
c.1947 - c.1953: The print codes used on small-scale maps during this time are not nearly as informative as the previous codes.
They are simply an indication of a print job reference, and are given the name unique numbers because no two sheets/revisions would have the same print code.
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Subsequent revisions or printings had a print code added to them in the style 6.12.