ONS Postcode Products
The National Statistics Postcode Lookup (NSPL) and ONS Postcode Directory (ONSPD) allocate UK postcodes to a wide range of geographies (for example, local authority districts, census small areas). Northern Ireland postcodes are included as a part of this.
For example, you have data which includes postcode addresses and you want to know in which Northern Ireland constituency these records relate to. You can use these products as a lookup table to match find which constituency each postcode is in.
Geographical areas are referred to by their ONS code (rather than by name). You can find the area names that these codes are associated with on our datastore here. Please also note that while the coordinates are tagged as OS grid references (i.e. the fields
osnorth1m), the NI postcodes in the datasets use Irish Grid References. Standard decimal degrees Latitude and Longitude coordinates are also present.
Because these are not NI-specific datasets you will need to filter out non-BT** postcodes. This is easily achieved: for example, in Excel by using a text filter on the first column (
pcd) and for 'Begins With...' enter 'BT'. You can therefore continue to work with the NI postcodes only in a reduced file size. There are also some slight differences between names used for areas as they are commonly referred to in NI and those used for GB (e.g. ONS 'output area' for GB is similar to 'small area' commonly referred to by NISRA). We recommend referring to the user guide and to our names and codes dataset if you are unsure what the column field refers to.
Three variations of formatting for each postcode are presented:
pcd: 7-character version of the postcode (e.g. 'BT1 1AA', 'BT486PL')
pcd2: 8-character version of the postcode (e.g. 'BT1 1AA', 'BT48 6PL')
pcds: one space between the district and sector-unit part of the postcode (e.g. 'BT1 1AA', 'BT48 6PL') - possibly the most common formatting of postcodes.
Difference between NSPL and ONSPD
The NSPL and ONSPD are basically the same product, but with the main difference being the methodology used to allocate areas to postcodes. While the ONSPD uses a 'point in polygon' method to assign postcodes to each type of geographic area, the NSPL allocates higher geographies using the postcode's Small Area as the building block while applying a best-fit method. For more detail, see this download (zipped PDF).
Therefore, while the ONSPD is more exact, it differs from the metholodolgy used by the NSPL in producing National Statistics. This has an effect when a Small Area crosses a higher geography boundary, such as a constituency. Users of National Statistics should therefore prefer the NSPL (as it is coherent with the ONS Geography Policy), while general users prefer the ONSPD.
Licensing: difference between GB and NI licences
While the GB postcode data is provided under the Open Government Licence, for the Northern Ireland data (i.e. all postcodes starting with “BT”) a more restrictive Northern Ireland End User Licence (for internal business use only) applies.
Use of the Northern Ireland data contained within the ONS postcode products constitutes acceptance of the Northern Ireland licensing terms and conditions. For commercial use, you need to obtain a separate licence for commercial use directly from Land and Property Services.
Data and Resources
Dataset InfoThese fields are compatible with DCAT, an RDF vocabulary designed to facilitate interoperability between data catalogs published on the Web.
|Spatial / Geographical Coverage Area (WKT)|
POLYGON ((-8.18481 55.3541, -5.40527 55.3541, -5.40527 54.0465, -8.18481 54.0465, -8.18481 55.3541))
|Spatial / Geographical Coverage Location|
See user guide provided as part of download package