GENERAL DESCRIPTION OF SERIES 7, ONE INCH SCALE ORDNANCE MAPS OF ENGLAND AND WALES
The Ordnance Seventh Edition was the first true survey after the 2nd World War; the Series 6 maps having been from surveys of the 1930’s. Series 7 maps were usually published from Chessington following bomb damage to the Southampton OS Office.
They doe not cite revision from earlier survey work.
The standard dates are c1952 with revisions to c.1966 The earlier publications of the 1950’s tend to have shorter covers and the sheet folds to 30 rather than 24.
Series 7 maps tended to be about 27 inches by 32 inches and show an area of 40 km of longitude by 45 km of latitude.
The maps were lithographed. It is said that in the preparation of the 6th series, maps south of Birmingham used masters which were already lithographic, but north of that latitude the masters were still engraved. By Series 7, the age of the Engraved or electrotyped map was gone.
There were 190 maps in the Series, numbered north to south. No 1 was North Shetland; No 190 was Truro. The last maps published were of Shetland, and one often reads on the back cover a 1961 “expected completion date” for the entire series.
The National Grid of 1 and 10 kilometre squares did not alter from Series 6 – Point “00” on the grid was located off South West of Cornwall. This was referred to as a False Datum- because the point was arbitrary- unlike the Sea Level Datum. It was fixed there to make all map references “positive”: that is, east or north of the Datum . The exception was Rockall.
The scale was expressed as 1 inch or 1:63,360. Scales in yards and Kilometres are also given. For many decades the Ordnance Survey had been metric but the maps were given an Imperial measurements gloss for the public.
The datum for measurements of altitude is not stated except as “Mean Sea Level” but since 1915 this was LWMMT at the Tidal Observatory, Newlyn, Cornwall. Series 7 is fully re-levelled, so no reference is made to the older Liverpool Datum.
This re-levelling to the new datum at Newlyn LWMMT from the old datum at Liverpool LWMMT was slow; often large scale maps cite dates as late as 1950-52 for re-levelling. The new readings were undertaken as civil engineering projects were carried out. Thus a 1932 re-levelling date on a 6” map probably indicated the year that mains water entered a rural district.
Series 7 did sometimes revise using aerial photography, which had been introduced in the 2nd World War. Like the National Grid, it was a spin-off of military usage.
In this series, RAF and RNAS airfield from the 2nd World War are shown, usually if they are redundant. Operating military airfields may still be redacted, as are naval bases. Old RAF fields are usually shown blank and crossed by footpaths with the word “Airfield” on them. Rarely are they surveyed and when they are, they usually show a runway plan in the form of a number “4”. Some research is needed to establish the original airfield name, which might not have been that of the nearest village. A few are named thus: “Wattisham Airfield”. All military airfields were RAF or RNAS- even if operated by the USAF, RAAF, RCAF or RNZAF.
Covers were 8 ¼ inches by 5 inches. Some early ones are shorter and fold the bottom margin in-to accommodate the same sized sheet. The shorter format is roughly 7 1/2 inches by 5 inches.
On Series 7 covers, Scottish Maps had a different coat of arms: a Lion Rampant.
Original Series 7 covers are vermilion and off-white with red and black lining and lettering, the Royal Arms do not say either GR or ER. The edition number was at top right and on the front cover was a cartouche map of the district shown. The cover aesthetic was not unlike that of Penguin Book. They only have gloss covers in the latest Series 7 maps.
All editions cited revision and publication dates on the cover. Note the Edition date is not the printing date which was generally later.
The covers of Series 7 maps were all hinged; Scottish maps had floating covers on Series 6 maps.
Urban areas were grey with white roads. This allowed major buildings to be rendered black, named, and clearly seen: thus solving a major fault on the Series 6 maps which has rendered urban areas black.
One inch maps do not show bomb or war damage- though a considerable amount remained as this survey was being carried out. One has to fine 25” or 50” surveys- used by the Land Registry and Planners for the word “ruin” to be seen on buildings, plots and parcels of land into the 1960’s. Roman names were written under the modern name thus “CAMVLODVNVM”- using that Latin form.
The greatest ambiguity on any Series 7 map concerns land use.
Woods were shown as deciduous, coniferous or mixed (that was a change), Parks were grey stippled, as were tidal reaches, perhaps these might be seen as the last aesthetic remnants of the engraved or electrotyped map. Arable land was not differentiated from pasture and orchards were not differentiated between Apple, Pear, Cherry, Plum, and Damson. Hop gardens were not shown as orchards, they were marked as open arable land. Deciduous or Coniferous woods did not indicate age. One cannot prove the existence old, primeval or ancient woodland from the symbols an OS map. On English maps one can assume that a coniferous wood is a plantation as the tree is not endemic.
This was the first and last survey to show the full British Railways’ network. So the company names had gone and “British Railways” was unnecessary- being universal. The maps were contemporary to many line closures and these were marked with white dots at the stations. On the early 20th century OS maps a white dot just indicated a station. Occasionally the map post dated an early closure and the line was shown only by “track of old rly”. A line with white marked stations was not necessarily a closed line- for it may have remained open for freight use.
A few branch lines were open on Series 6 but gone by Series 7. It was common on series 7 maps to see a line being “rolled back”: closed with white station over part of its course and “track of old rly” over another part. This provided interesting historical information- showing the process of closure and track lifting.
British Railways was formed in 1948 under the Attlee government and dismantled in 1997 under the Major government. It was an amalgamation of the Big Four 1921-1923 companies: L&NER, LM&SR, SR and GWR, as well as some smaller networks such as the Midland and Great Northern Railway, Norfolk and Suffolk Joint Committee Railway, and Cheshire Lines. From 1995 it was known as BR.
The Series 6 maps were contemporary to the phasing out of steam traction- the last steam hauled train was in 1968. Lines were electrified or changed to diesel traction. The Southern Region used the 3rd rail system whereas the rest of the country used overhead lines and pantographs. On the map double lines are shown with a continuous black line and single lines with a black and white dashed line. Principal stations were shown rectangular, other stations were marked as circular- both were red. Level crossings were no longer marked with a red diagonal cross which was a remnant, on Series 6 maps, of their subsidiary used by War time flyers of the ATA
Until 1962 the network was technically “The Railways of the Railway Executive of the British Transport Commission”.
Series 7 maps named A & B roads with their MOT numbers. A roads were red, B roads were bisque brown and none numbered minor roads were yellow. Unmetalled roads were white and footpaths, tracks and bridle paths were shown with a dashed black line. Maps always state that an OS marked route does not prove a legal right of access or usage. Motorways were rare but can appear on late revisions. A dashed red line indicates an unfinished or proposed new road.
Generally Series 7 maps looked less busy than Series 6 because there was less black and finer lines. The paper was more bleached that previously but without the stark whiteness of later maps. The outer border cited degrees and minutes of longitude and latitude.
Contours were surveyed in 100’s of feet: 50 ft contours were interpolated. Contours are russet brown but shown with thinner lines which could clutter Series 6 maps.
Submarine contours are still shown to 5 and 10 fathoms.
Series Seven maps did not show Admiralty soundings, as much earlier terrestrial Ordnance 1” maps had done. But the shallows and tidal flats were shown in great detail in a grey stipple- and the major tidal flats were named. The marine contours of a Series 7 map were drawn at 5 and 10 fathoms. Inland waters were measured in feet not fathoms (if measured at all). Bathymetric surveys can be quite old- 1870’s-1900’s and were seldom repeated. Some inland waters were cited with a height above sea level at the water surface. Fathoms were measured from the almost the same datum as land altitude: LWMMT Newlyn. A sea chart defines: “Chart Datum is the level below which the tide never falls”. which is not quite the same as the terrestrial LWMMT (Low Water Mark of Medium Tides). A fathom is 6ft (1.8288 metres), anciently defined as the distance between a man’s outstretched arms; so the two contours on a Series 7 OS map equated to 30ft and 60ft sea depth. A “shallow” is water which can be measured by plumb line: called a “sounding”. Water deeper than 100 fathoms is “beyond sounding”. Interestingly, burial at sea had to be at least 6 fathoms or “Deep Six”. Technically a Royal Navy fathom is 1/1000 of an Imperial Nautical or Sea Mile, which is 6.08 ft.
The hydrographic significance of the 5 fathom line on a Series 7 map was that water less than 5 fathoms was measured in feet. Of course sea depth needs a datum, but fresh water depth cannot have one- for its surface never equates to a standard datum and can be at any altitude.
The altitude of a lake bed must be calculated arithmetically; it equals terrestrial altitude at the lake’s surface minus the greatest bathymetric measurement.
Bathymetric data, common in Scotland, is rare in England and Wales with the Lake District being a notable exception. Any lake adapted for reservoir use- such as Hawes Water or Thirlmere, did not have bathymetric data because its water level was variable. Reservoirs, such as Abberton, often showed intricate parish boundaries, following then flooded fields and lanes.