SABRE Maps/Half Inch coverage project

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

Key

Available on SABRE Maps

Online, but needs replacement source

Unconfirmed Revision

Within the pipeline

Pipeline (Military edition)

Acquired but not scanned

Copy needed

In copyright (copy available)

In copyright (copy needed)

No map printed (or empty cell)

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.

Key

Available on SABRE Maps

Online, but needs replacement source

Unconfirmed Revision

Within the pipeline

Pipeline (Military edition)

Acquired but not scanned

Copy needed

In copyright (copy available)

In copyright (copy needed)

No map printed (or empty cell)

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

Key

Available on SABRE Maps

Online, but needs replacement source

Unconfirmed Revision

Within the pipeline

Pipeline (Military edition)

Acquired but not scanned

Copy needed

In copyright (copy available)

In copyright (copy needed)

No map printed (or empty cell)

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