HP21 postcode district

Postcodes and sectors

725 of the district's 1,099 postcodes are live in the ONS Postcode Directory of August 2026. A postcode directory says whether a code is in use, never who is there. The live postcodes centre on 51.80513, -0.80587, which locates the district, not a building.

Companies registered in HP21

Companies House lists 1,483 companies with a registered office in HP21; 88 of them at addresses shared by 25 or more companies (1 October 2026 snapshot). 25 is the count at which the address lookup reports a company cluster.

Places OS Open Names lists for HP21

• Aylesbury
• Buckinghamshire
• South East

Roads filed under HP21

Named roads first, then numbered ones. A road is filed under one district even where it runs through several, so a street missing here may be listed under a neighbouring district — which is why the address lookup never calls a British street absent. Great Britain has no open register of buildings, so a listed road never means a building on it exists.

• Aidan Close
• Alham Road
• Allonby Way
• Alwin Close
• Ambleside
• Anns Close
• Anson Close
• Anton Way
• Aplin Road
• Arnold Court
• Ashbourne End
• Ashford Close
• Ash Grove
• Athens Avenue
• Atlanta Way
• Avon Place
• Ayres Close
• Ballard Close
• Barcelona Boulevard
• Barley Crescent
• Barnard Crescent
• Bateman Drive
• Battersby Mews
• Batt Furlong
• Baynton Road
• Beaconsfield Road
• Bearbrook Close
• Beaufort Close
• Bedgrove
• Bedwyn Walk
• Beech Green
• Beethoven Drive
• Birch Court
• Bishops Walk
• Blackwater Drive
• Blenheim Place
• Blyth Close
• Bodiam Close
• Bond Close
• Bonham Close
• Bowler Road
• Bowmont Drive
• Bracken Way
• Braddenham Walk
• Braden Close
• Brahms Lane
• Brent Path
• Brentwood Way
• Briskman Way
• Britten Close
• Brotheridge Court
• Brubeck Road
• Burrell Close
• Buttermere
• Byron Road
• Caldicot Close
• California
• Camborne Avenue
• Cam Mead
• Canford Court

Check an address in HP21

Check an address in HP21

The same road list through the API, from the outward code alone:

curl "https://spaw.co/api/v1/address/streets?country=GB&postal_code=HP21" \
  -H "Authorization: Bearer $SPAW_KEY"

Common questions about HP21

What does an HP21 postcode tell you?

That the address lies in the HP21 district of the HP (Hemel Hempstead) postcode area, and the place OS Open Names most often lists first for its postcodes is Aylesbury. The district alone does not place a street: the inward half of the full postcode narrows the address to one of the district's 725 live postcodes.

Where the counts come from

• ons-postcode-directory · version 2026-08 · Contains ONS, OS and Royal Mail data © Crown copyright and database right 2026, Open Government Licence v3.0. Northern Ireland postcodes are excluded: their reuse needs a Land & Property Services licence.
• os-open-names · version 2026-11-01 · Contains OS data © Crown copyright and database right 2026, Open Government Licence v3.0.
• uk-companies-house · version 2026-10-01 · Companies House free company data product, Open Government Licence v3.0

What each figure means, and what a district page never says, is set out in Reading a British postcode district page; the glossary defines a postcode district, a postcode area, a postcode directory and a street register.

Data synced on 2026-11-01: the newest version among the datasets listed above.

Districts nearest HP21

• HP201.7 km
• HP222.5 km
• HP192.6 km
• HP176.5 km
• HP279.5 km
• HP2310.0 km
• HP1811.3 km
• HP1612.9 km
• OX3913.8 km
• OX914.4 km
• LU715.1 km
• HP416.8 km
• Every district
• How a British address is written
• Check any address

distance between the districts' centroids