HA3 postcode district

Postcodes and sectors

1,262 of the district's 2,160 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 51.59381, -0.32092, which locates the district, not a building.

Companies registered in HA3

Companies House lists 10,222 companies with a registered office in HA3; 2,813 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 HA3

• Greater London
• London
• Harrow
• Kenton
• Brent
• Stanmore

Roads filed under HA3

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.

• Abercorn Gardens
• Aberdeen Road
• Adderley Road
• Addiscombe Close
• Alicia Avenue
• Alicia Close
• Alicia Gardens
• All Saints Mews
• Alma Row
• Alveston Avenue
• Annette Close
• Archery Close
• Arnold Close
• Artisan Place
• Ashridge Close
• Astall Close
• Aston Avenue
• Athelstone Road
• Augustine Road
• Avondale Road
• Bancroft Gardens
• Bancroft Road
• Barchester Road
• Barratt Way
• Baslow Close
• Beaufort Avenue
• Becmead Avenue
• Bellfield Avenue
• Belmont Circle
• Belmont Road
• Belsize Road
• Belvedere Way
• Bengarth Drive
• Birch Park
• Bishop Ken Road
• Blackwell Close
• Boniface Gardens
• Boniface Walk
• Borrowdale Avenue
• Bouverie Gardens
• Boxmoor Road
• Boxtree Lane
• Boxtree Road
• Bradenham Road
• Brampton Grove
• Brancker Road
• Branksome Way
• Briar Road
• Brinsley Road
• Broadlawns Court
• Brookfield Crescent
• Brookshill
• Brookshill Avenue
• Brookshill Drive
• Brookside Close
• Bruce Road
• Bulmer Gardens
• Burnham Close
• Bush Hill Road
• Byron Road

Check an address in HA3

Check an address in HA3

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

curl "https://spaw.co/api/v1/address/streets?country=GB&postal_code=HA3" \
  -H "Authorization: Bearer $SPAW_KEY"

Common questions about HA3

What does an HA3 postcode tell you?

That the address lies in the HA3 district of the HA (Harrow) postcode area, and the place OS Open Names most often lists first for its postcodes is London. The district alone does not place a street: the inward half of the full postcode narrows the address to one of the district's 1,262 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 HA3

• HA11.9 km
• HA72.1 km
• HA23.6 km
• HA83.8 km
• HA94.4 km
• HA54.5 km
• NW94.6 km
• HA04.9 km
• UB66.2 km
• WD236.3 km
• WD196.3 km
• NW76.5 km
• Every district
• How a British address is written
• Check any address

distance between the districts' centroids