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SABRE Maps/Half Inch coverage project

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See Also: SABRE Maps/MOT coverage project

This project is to provide online coverage of the various OS, OSI and OSNI maps at the Half-Inch scale to SABRE Maps, focussing primarily on those maps that include road numbering on them, although coverage of OS Ministry of Transport Road Maps are detailed elsewhere due to their extreme historical importance.

Maps at the half-inch scale are unusual in Ordnance Survey GB, and most familiar to us because the MoT maps are based on (old) Half-Inch outline maps with the coloured overlays, which is why then-new bypasses look a bit odd sometimes, because there's no road underneath the overlay. They started to fall out of favour around World War 1, though some sheets continued into the late 1920s and early 1930s before being cancelled, though there are some "District" sheets that continued to be produced until just after World War 2. These District sheets are invaluable to us, as they contain road numbering at a more detailed scale than Quarter Inch maps, usually in areas where there was no One Inch Fifth Edition coverage. Bear in mind that the older Half Inch series confusingly comes in covers called Ordnance Survey Road Map, but these are based on the pre-World War 1 series with no road numbers printed on them, and are not the same thing as either the OS Ministry of Transport Road Maps or the later National Yard Grid district maps - both of which do contain road numbering information.

There was an attempt to bring back OSGB maps at the Half-inch scale across the whole of Great Britain in the late 1950s and early 1960s, but there were only ever five maps produced at that scale (and one further to proof stage), plus one Tourist Map before once again the series was cancelled, and there's been no real attempt since 1962 to publish a series of maps at this scale in Great Britain.

However, in Ireland it's a different story. Half inch maps produced by both OSI and OSNI were common through to the late 1980s, and relatively large numbers have survived - meaning that they're a valuable resource for us to have.

Which projection type are these maps?

See Also: SABRE Maps/Calibrating

Maps at the Half-Inch scale use various projections, and so care will be needed to select the correct one.

English OS Half-inch maps of the 1930s and 1940s use the National Yard Grid, even if it is not specifically printed on that revision; whilst Scottish sheets of that time use the Bonne (Scotland) projection. All post-1950 sheets of Great Britain use the OSGB National Grid.

Post-1955 OSI Half-inch maps have Irish Grid references printed on them, but in common with earlier maps they actually use the Bonne (Ireland) projection. Georeferencing using the Irish Grid on these maps will result in poor alignment and the full map area not being available.

In comparison, the OSNI Second Series maps really do use the Irish Grid, and should be georeferenced accordingly.


How do I find out the date of the map?

Most OSGB Half Inch Second Series maps have revision codes that look like this One Inch Seventh Series example, B/* in this case, which dates the map to 1966 rather than the 1962 copyright date
Those few OSGB Half Inch maps from the 1930s have revision codes that look like this One Inch Fifth Edition example, 3035 in this case, dating the map to 1935
Most OSI Half Inch maps have revision codes that look like this example, 5-57 in this case, which dates the map to May 1957
OSNI Half Inch Second Series maps have revision codes that look very similar to OSGB ones, A in this case
See Also: SABRE Maps/OS Copyright

Annoyingly, Ordnance Survey GB didn't actually put the exact date of the map on each map. The date that appears on the map (usually with the words First published by the Director General at the Ordnance Survey Office) often is not the correct date of the map, but the date of the first revision of the map. Roads, along with other minor corrections were actually updated on every revision, so the map you have may be from a number of years away from the most obvious date.

Revision codes on OS GB Half Inch sheets can be found in one of two places. In the maps from the early 1930s, they are located right at the bottom right of the map sheet, underneath the margin texts; whilst in most sheets, they are located immediately under the bottom left corner of the maps themselves, between the map and the key. Just occasionally they're located immediately under the bottom left of the key.

Irish maps on the other hand, generally have some of the simplest revision code information to find - they're generally bottom right just underneath the map, with extensive dating information to the right. Be aware that a number of early Irish Half-inch maps don't actually have specific revision codes on them, so if you have a pre-Irish Grid map, and there isn't one in the right location, then there probably isn't one at all!

Second Series Ordnance Survey of Northern Ireland half-inch sheets however have a very similar lettering system to OSGB maps, again bottom left just underneath the map itself. However, it appears that OSNI only ever printed one edition of each of the four sheets.

Revision codes are the best way of dating the maps, and so this information is extremely valuable to capture. On SABRE Maps, where we have it the revision code appear in the sheet name heading area.

Which maps are actually available?

If two revisions were printed in a single year, then the one nearest to the centre of the year is listed as being from that year, and the other revision shifted into the earlier or later year as appropriate. Only standard civilian colour editions are listed.

Only Second Series and other maps believed to contain road numbers are included.

The dating of the map revisions is taken from the Charles Close Society Half Inch Cartobibliography.

Key to tables

Available on Maps Unconfirmed Revision Within the pipeline Not currently available Still within copyright

Ordnance Survey Half-Inch

National Yard Grid maps

Sheet Name 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1945 1946
- Peak District 8036 10039
- The Cotswolds 7050/32 10,000/34 100/37
- Birmingham District 10,000/34
- Greater London 5035 6040 8045/Cr 30046
- Island of Skye 4000/32 30/37

Note: the Island of Skye map is technically not a National Yard Grid map, but is instead on the Scottish Bonne projection. It is, however, visually similar to the remainder, and from the same period.

National (Metric) Grid maps

Note: Sheet 37 (Leicester) was never released, but a proof copy exists, and was republished by the Charles Close Society in 2012. Their re-publication is therefore still within copyright and cannot be used without permission.

Sheet Name 1956 1957 1958 1959 1960 1961 1962
28 Snowdon A
36 Birmingham A A/
37 Leicester A
39 Norwich A
43 Greater London A
51 Canterbury A
Sheet Name 1966 1967 1968 1969 1970 1971 1972 1976 1979 1981 1984 1986
Tourist Snowdonia A A/ A//* A//*/* A//*/*/* A//*/*/*/* A//*/*/*/*/* A//*/*/*/*/*/*

Ordnance Survey Ireland 1945-1970

OSI Half-Inch sheets regularly changed their names, but not their layouts or alignments. All names are therefore given within the "Name" column.

Sheet Name 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970
1 Londonderry
Letterkenny
North Donegal
no code no code 11.55 9.57 4.61 5.64 9.67 10.69
2 Coleraine
North Derry-North Antrim
1950/46 no code 12.57 11.62 8.69
3 Donegal
South Donegal
no code no code no code 6.57 8.61 11.64 11.67 12.69
4 Omagh
Derry-Tyrone
12.56 1.58 4.64
5 Belfast 2450/46 no code 1962
6 North Mayo no code 12.56 8.62 8.67
7 Sligo
Sligo-Leitrim
1950 7.57 9.61 4.65 3.69
8 Monaghan
Monaghan-Armagh
no code 3.56 2.61 6.67 12.69
9 Newry
Mourne Mountains
no code 9.55 8.58 4.67 8.70
10 Westport and Clifden
Clifden
Connemara
no code no code 6.57 10.60 1.64 9.65 1.68 12.69
11 South Mayo no code 3.57 9.61 9.65 7.68
12 Longford no code 8.56 10.59 8.63 12.67
13 Drogheda
Meath
no code no code 1949 1950 11.55 5.58 10.62 8.65 1.68 9.70
14 Galway
Galway Bay
no code 10.55 5.57 3.61 5.65 5.68
15 Birr
Galway-Offaly
no code no code 11.56 8.60 8.64 9.67
16 Dublin
Kildare-Wicklow
no code no code 6.47 6.48 5.49 7.50 1.56 1.58 10.60 4.63 1.65 9.66 8.68
17 Limerick, Ennis and Listowel
Mouth of the Shannon
Shannon Estuary
no code 5.55 3.58 7.62 9.67 1.71
18 Templemore and Tipperary
Tipperary
no code 1951 7.56 4.60 4.64 7.68
19 Carlow
Carlow-Wexford
no code 1947 1949 6.56 2.59 2.63 7.65 2.68
20 Killarney and Dingle Bay
Dingle Bay
no code 1950 2.55 4.58 4.62 7.64 10.66 1.68 9.69
21 Killarney
Kerry-Cork
no code 10.56 9.60 7.64 7.67 11.69
22 Cork and Lismore
East Cork-Waterford
no code 1949 12.55 9.57 1/61 9.64 10.68
23 Waterford and Wexford
South Wexford
no code 7.56 8.61 3.65 8.68
24 Bantry
West Cork
1948 1949 no code 11.54 9.57 11.60 6.63 5.65 8.68 5.70
25 Cork
South Cork
1948 1951 8.56 9.61 9.64 6.68

Ordnance Survey Ireland District maps

Sheet Name 1963 1964 1965 1966
- Barrow and Nore Basins 9.63
- The Burren 12.64
- Cill Dalua: Killaloe 12.64
- Clew Bay 9.63
- Killarney 9.63
- Manorhamilton 1.64
- County Limerick 9.66

Ordnance Survey Northern Ireland Half-Inch Second Series

Sheet Name 1968 1969 1970
1 The North-west A
2 The North-east A
3 The South-west A
4 The South-east A




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