What is a UDPRN?
A Unique Delivery Point Reference Number identifies one delivery point, meaning one premise, in Royal Mail's Postcode Address File. Royal Mail introduced it in 2004 and inserted it into PAF.
Its properties:
- An 8-character numeric code
- One code per delivery point
- Assigned automatically when a new delivery point is added to PAF
- Far less likely to be reused than the PAF keys that preceded it
Why store a UDPRN?
Because the address text moves and the identifier does not. Street names get corrected, localities get added, a building gets renamed. If you stored only the printed address, you have no way of telling a corrected record from a different property.
Every address returned by a postcode lookup or address search carries its udprn. Store it alongside the address and you can:
- Re-fetch the current addressing information for a premise at any time
- Detect a premise that has been decommissioned or demolished, because the lookup stops resolving
- Deduplicate customer records that hold two spellings of the same address
How does a UDPRN differ from a UPRN?
They come from different bodies and cover different things. Both are returned on every Ideal Postcodes UK result, so you do not have to choose.
The UPRN guide covers the property identifier in full.
How do you look up an address by UDPRN?
Send the code to the /udprn endpoint. Below, ak_test is a public test key and 23747771 is 10 Downing Street:
https://api.ideal-postcodes.co.uk/v1/udprn/23747771?api_key=ak_test
A single address object comes back in the result attribute:
{
"result": {
"postcode": "SW1A 2AA",
"postcode_inward": "2AA",
"postcode_outward": "SW1A",
"post_town": "London",
"dependant_locality": "",
"double_dependant_locality": "",
"thoroughfare": "Downing Street",
"dependant_thoroughfare": "",
"building_number": "10",
"building_name": "",
"sub_building_name": "",
"po_box": "",
"department_name": "",
"organisation_name": "Prime Minister & First Lord Of The Treasury",
"udprn": 23747771,
"postcode_type": "L",
"su_organisation_indicator": "",
"delivery_point_suffix": "1A",
"line_1": "Prime Minister & First Lord Of The Treasury",
"line_2": "10 Downing Street",
"line_3": "",
"premise": "10",
"longitude": -0.12767,
"latitude": 51.503541,
"eastings": 530047,
"northings": 179951,
"country": "England",
"traditional_county": "Greater London",
"administrative_county": "",
"postal_county": "London",
"county": "London",
"district": "Westminster",
"ward": "St. James's",
"uprn": "100023336956",
"id": "paf_23747771",
"country_iso": "GBR",
"country_iso_2": "GB",
"county_code": "",
"language": "en",
"umprn": "",
"dataset": "paf"
},
"code": 2000,
"message": "Success"
}
Full parameters and error codes are in the UDPRN API documentation.