CM20 postcode district

Postcodes and sectors

629 of the district's 1,249 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 51.77566, 0.10276, which locates the district, not a building.

Companies registered in CM20

Companies House lists 5,572 companies with a registered office in CM20; none of them at an address 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 CM20

• Eastern
• Harlow
• Essex
• East Hertfordshire
• Hertfordshire
• Eastwick
• Gilston

Roads filed under CM20

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.

• Adams House
• Altham Grove
• Amberry Court
• Arbour Mews
• Arkwrights
• Ash Tree Field
• Bishop Close
• Blackbush Spring
• Blackbush Springs
• Bowhill Way
• Bowlby Hill
• Bracewell Place
• Bramble Rise
• Broadfield
• Broad Walk
• Bromley Close
• Broomfield
• Burnt Mill
• Burntmill Close
• Burntmill Lane
• Canons Gate
• Central Road
• Cherry Tree Lane
• Chestnut Lane
• Churchfield
• Civic Walk
• Cockrobin Lane
• College Gate
• College Square
• Commonfields
• Cooks Spinney
• Crown Gate
• Dads Wood
• Dovehouse Croft
• Dukes Park
• East Gate
• East Road
• East Walk
• Eastwick Hall Lane
• Eastwick Road
• Edinburgh Gate
• Edinburgh Place
• Edinburgh Way
• Elizabeth Way
• Felmongers
• Fesants Croft
• Fifth Avenue
• First Avenue
• Fold Croft
• Foster Court
• Gilston Park
• Gladwin Way
• Glebelands
• Great Plumtree
• Greenhills
• Green Park
• Halling Hill
• Hammarskjold Road
• Hamstel Road
• Hankin Road

Check an address in CM20

Check an address in CM20

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

curl "https://spaw.co/api/v1/address/streets?country=GB&postal_code=CM20" \
  -H "Authorization: Bearer $SPAW_KEY"

Common questions about CM20

What does a CM20 postcode tell you?

That the address lies in the CM20 district of the CM (Chelmsford) postcode area, and the place OS Open Names most often lists first for its postcodes is Harlow. The district alone does not place a street: the inward half of the full postcode narrows the address to one of the district's 629 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 CM20

• CM182.3 km
• CM192.8 km
• CM922.9 km
• CM173.0 km
• CM215.0 km
• EN117.8 km
• SG108.2 km
• CM168.4 km
• SG129.3 km
• EN109.6 km
• EN910.7 km
• CM2311.4 km
• Every district
• How a British address is written
• Check any address

distance between the districts' centroids