Owen Boswarva's blog

This is the latest in a series of blog posts about the campaign for open address data in the UK. Previous posts are listed at the bottom.

In this post, I describe a new open address dataset released by Conwy County Borough Council (Cyngor Bwrdeistref Sirol Conwy).

Background

As related in previous posts, I have recently been requesting Council Tax address datasets from a number of local authorities in England, and asking for permission to re-use the data under the terms of the Open Government Licence. I have also submitted similar requests to some local authorities in Wales and Scotland.

I have created a landing page on my Datadaptive site with download links and other information about the Council Tax address datasets released as open data so far:

www.datadaptive.com/addr/

Release from Conwy County Borough Council

The latest council to release its Council Tax address list is Conwy County Borough Council in Wales.

The Council disclosed the requested information, and confirmed permission for re-use under the terms of the Open Government Licence, without difficulties.

You can download my correspondence with the Council: CT_address_list_Conwy_29914_[NO_DATA_correspondence_only].zip (0.37 MB).

Thanks to Council staff for facilitating the disclosure and open licensing of this data.

Access to this dataset

I am not publishing Conwy County Borough Council's address dataset here, due to the non-specific but lingering risk of further unsubstantiated claims of infringement from Ordnance Survey and GeoPlace LLP. You can read more about that issue in my recent blog post.

However, there is nothing to stop you asking the Council directly for a copy of the data file. For tips on submitting access to information and re-use requests see this other blog post. My requests to Conwy County Borough Council were submitted on 18 May 2026 and the Council's references are 29912 and 29914.

More about Conwy County Borough Council's address dataset

Conwy County Borough Council has disclosed its Council Tax address dataset to me in the form of a CSV file 'FOI 29913.csv' that contains 58,510 records. Each record includes the full address (split into four fields), postcode, local property reference, Unique Property Reference Number (UPRN), and Council Tax valuation band, for a domestic property in the Conwy County Borough Council area.

The dataset appears to be well-maintained but the address information contains some inconsistent formatting, extraneous characters, and typos.

UPRN values are missing for 3,608 (6.17%) of the 58,510 records in the list. UPRN values in four other records are obviously wrong, but for one of those the likely correct UPRN can be inferred from UPRNs given for neighbouring properties. Following those corrections, 51 of the UPRNs do not match to records in the May 2026 release of OS Open UPRN product. The vast majority of the property records in the dataset can be geocoded for mapping and geographic analysis of domestic properties in the Conwy County Borough Council area, but the lack of completeness may be relevant for some purposes.