I'm currently working in a database which stores mainland British locations as their Ordinance Survey Northing/Easting values. Can points in Ireland (primarily Northern Ireland) be accurately represented via simply adding to the datum or is the curvature too much?

  • 1
    You can use it in Northern Ireland its just not as suited as the Irish grid Commented Nov 3, 2015 at 12:08
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    There is some difference between the British and Irish coordinate systems which might reflect your data. The Irish Transverse Mercator was established for the entire island of Ireland (including Northern Ireland) which might better suit your needs.
    – Joseph
    Commented Nov 3, 2015 at 12:09
  • Thanks, our current third party API uses the Irish grid so I was hoping for an easy translation.
    – Furby
    Commented Nov 4, 2015 at 8:10

1 Answer 1


Technically, yes, depending on how good the algorithm for transverse Mercator is in the software that you're using. The origin of BNG is 2 West, and Northern Ireland extends to 8 West. Six degrees from the central meridian (2 West) is not bad and should work fine for any standard implementation of transverse Mercator.

As mentioned in comments, it just isn't as suited to Ireland and Northern Ireland as the Irish TM coordinate reference system.

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