25" Second Edition O.S. maps

Scope and Content

Early to mid 20th Century, Ordnance Survey, 25" drawn revision maps, covering nearly all of Wales, except for most of Montgomeryshire.

Administrative / Biographical History

Produced by the Ordnance Survey, the maps are special, unpublished, revised states of OS 25" maps, re-drawn in black ink, over impressions of previous states, which are printed in blue ink. This alowed the cartographers to use the "blue" as a guide for features which had not changed, whilst drawing the revised state. The revised states could then be photographically copied, without the blue ink showing up. The maps are signed off by the Royal Engineer officers reponsible for overseeing the revisions at various stages. The maps were mainly produced for the Second Edition, from 1904-1908, but also cover revisions of various year editions up until 1943.


The maps are arranged by county in map number order.

Access Information

Material is on full public access.

Acquisition Information

Donated by the Public Record Office in 1980.


Edwards, G.M.

Other Finding Aids

There is a written catalogue of the maps, and they can also be accessed by a database on the RCAHMW GIS system.

Alternative Form Available

Original material held by National Monuments Record for Wales.

Conditions Governing Use

The maps are out of copyright.

Custodial History

The maps were originally deposited with the Public Record Office by the Ordnance Survey, at an unknown date. In 1980 the PRO began to destroy the collection, until the NMRW stepped in to provide it with a home. The destruction resulted in the loss of nearly all those maps which covered the county of Montgomeryshire.

Location of Originals

Original material held by National Monuments Record for Wales.

Geographical Names