What is it?

This is a collection of Administrative and Political boundaries for Great Britain.

Administrative Boundaries consist of:

  • EU Regions
  • Ceremonial Counties
  • Historic Counties
  • Counties
  • District, Borough and Unitary Authorities
  • Parishes

The Political Boundaries consist of:

  • Electoral Divisions within Counties
  • Electoral Divisions within District, Borough and Unitary Authorities
  • Electoral Regions within Scotland and Wales
  • Wards within District, Borough and Unitary Authorities
  • Wards within Wales
  • Westminster Constituencies (all of GB)
  • Greater London Constituencies
  • Polling Districts in England


Where does it come from?

Ordnance Survey


How often is it updated?

This set of layers are updated every 6 months, typically in May and November.


What area does it cover?

Great Britain


How might you use it?

These datasets may be useful for:

  • discovering the area that your parish council actually covers!
  • Comparing the difference between wards and constituencies
  • Seeing what polling districts are in your area


Data Licence

Provided through Open Government Licence (V3).


Technical Blurb

These layers all contain polygons and are styled to be transparent within them and only show a border. The styling is fixed and consistent across all Parish Online accounts (e.g. all parish boundaries are blue).

By clicking on a polygon the Info Click panel will show the area in the units you specify.



Why is the blue parish boundary layer different to the boundaries marked out on the Ordnance Survey maps?

You would have thought that the boundary shown in the Ordnance Survey MasterMap layer (the most detailed one in Parish Online) would have the same boundary information as the individual boundary layers, also provided by Ordnance Survey?! Here's an example of what we menan:

As you can see in the image above, the pink dashed line (embedded in the OS MasterMap layer) is quite different to the blue line (the individual parish boundary layer).

We asked Ordnance Survey about this and the difference is due to the blue parish boundary layer being downsampled (also known as generalised or deresolved). The blue layer has been made openly available and free to download and as part of that process it's downsampled to a less-detailed product and is suitable to be viewed at a scale of 1:10,000. Whereas the original boundaries in OS MasterMap are suitable to be viewed at a scale of 1:1250.

So the short answer is; the pink lines are definitive, the blue lines are generalised and not definitive. So if you're making decisions based on the data, use the pink lines. Sometimes, you may even see a bit of pink text saying "DEF". This stands for "Definitive" as a reminder.

Why the blue line gets generalised by Ordnance Survey; we don't have the answer I'm afraid. It could be to do with how the open data initiative is funded, how the Geospatial Commission specified the initiative, or it could simply be to do with download size.

Another question to ask is why Parish Online continues to show the blue lines at larger scales than 1:10,000 when it's not suitable at that scale. Well, we tried that and found it to be very inconvenient as there were scales where you couldn't see the blue or the pink lines. Having both the generalised layer and the definitive layer is more convenient for the user.


Why does our parish boundary cross through houses? Which parish are they in?

It's a bit silly isn't it. How can half a property be in one parish, and half in another. This usually occurs where there are new housing developments but it can happen in rural areas, through farmhouses, example.

Having the official boundary changed is a complicated business as it has implications on council tax, census calculations, elections, all sorts. So it's not something that can be done just by moving some lines. If there are instances of this in your area we'd recommend getting in touch with your local authority to ask them. You could also switch on the Address layer in Parish Online to see what side of the definitive boundary the address point sits. This may give some clue... but again... it might not (take a look at the screenshot below). You would hope that common sense would prevail and that line of houses to the South are represented by the parish to the South.

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24 February 2021


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