What does an LL66 postcode tell you?

That the address lies in the LL66 district of the LL (Llandudno) postcode area, and the place OS Open Names most often lists first for its postcodes is Sir Ynys Mon. The district alone does not place a street: the inward half of the full postcode narrows the address to one of the district's 22 live postcodes.

LL66 postcode district

LL66, in the LL (Llandudno) postcode area, has 22 live and 1 terminated postcodes in the ONS Postcode Directory of August 2026, and OS Open Names files 2 roads under it.

postcode area	LL (Llandudno)
live postcodes	22
terminated postcodes	1
sectors	2
roads listed	2
companies registered	5
centroid	53.37980, -4.40827
directory release	2026-08

Postcodes and sectors

22 of the district's 23 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 53.37980, -4.40827, which locates the district, not a building.

sector	live	terminated
LL66 0	20	1
LL66 9	2	0

Companies registered in LL66

Companies House lists 5 companies with a registered office in LL66 (1 October 2026 snapshot).

Places OS Open Names lists for LL66

Sir Ynys Mon
Isle of Anglesey
Wales
Rhosgoch
Llanbabo
Bodewryd

Roads filed under LL66

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.

Bro Dawel
Pig y Rhos

Check an address in LL66

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

curl "https://spaw.co/api/v1/address/streets?country=GB&postal_code=LL66" \
  -H "Authorization: Bearer $SPAW_KEY"

Common questions about LL66

What does an LL66 postcode tell you?: That the address lies in the LL66 district of the LL (Llandudno) postcode area, and the place OS Open Names most often lists first for its postcodes is Sir Ynys Mon. The district alone does not place a street: the inward half of the full postcode narrows the address to one of the district's 22 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 LL66

LL682.8 km
LL674.8 km
LL695.9 km
LL716.1 km
LL708.2 km
LL7211.6 km
LL7811.9 km
LL7311.9 km
LL7413.7 km
LL6513.9 km
LL7614.3 km
LL7714.7 km
Every district
How a British address is written
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distance between the districts' centroids

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