Different easting/northing grid for Ireland

[agjmills]

Northern Ireland has a completly different easting/northing grid system, making them completly incompatible with the rest of the UK.

http://en.wikipedia.org/wiki/Irish_grid_reference_system#Eastings_and_northings

For example:

This postcode [Belfast]
http://www.uk-postcodes.com/postcode/BT155EG.html

Is apparently around 50metres away from this postcode [Cheshire]
http://www.uk-postcodes.com/postcode/CH642UZ.html

[agjmills]

In particular, it's a problem with the JSON that is returned, as there is no way to determine whether the easting/northing data is in the Irish Grid or not, whereas the HTML one tells you