This repository is for generating a parquet file with a lookup from:

1. postcode (pcds) -> local authority district (lad25cd)
2. local authority district (lad25cd) -> county and unitary authority code (ctyua25cd)

It uses as its inputs ONS datasets as follows:

1. National Statistics Postcode Lookup: https://geoportal.statistics.gov.uk/search?q=PRD_NSPL%20FEB_2026&sort=Date%20Created%7Ccreated%7Cdesc
2. Local Authority District to County and Unitary Authority Lookup in the UK: https://geoportal.statistics.gov.uk/datasets/3a815d3b4fa746a98390f52b1196d37d_0/explore

It is designed to produce a lightweight, flexible lookup for returning lower-tier or upper-tier local authority for any UK postcode.