SD930218A2, Ordnance Survey Revision Point photograph in Greater Manchester
Ordnance Survey postwar survey of Manchester
After WW2 up-to-date maps were needed and in Manchester the survey started in 1946. A network of centimetre accurate points was required that could be found again when a map was revised. Their position was recorded by these photographs which show a field labourer pointing to the exact spot with an arrow. The surveyors were behind the camera.
These Revision Points were often on streets corners and junctions, recording humble and everyday scenes, making them akin to a historic ‘street view’. It's not unusual to find over 100 photographs for a single kilometre square.
Once technology made the need for these photographs obsolete many were destroyed. However, Manchester Central Library preserved a large collection of 46,000 photographs covering much of Greater Manchester.
Apart from the date (if none they are 1949/1950) the boards record: the national grid reference of the square, two numbers denoting the 100m square, and a letter (usually A or B) as photos were in pairs. The other numbers are a reference for the film.