CM21 postcode area guide — East Hertfordshire
House prices, crime, broadband speeds, mobile signal, schools and demographics for the CM21 postcode district in East Hertfordshire — every official dataset on one page.
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Where is CM21?
Broadband & internet speeds in CM21
Strong coverage
Superfast (30Mb+)
93.8%
Ultrafast (300Mb+)
65.2%
Gigabit-capable
63%
Below USO (10Mb)
0.1%
Broadband availability in the CM21 postcode district (East Hertfordshire) is Strong — superfast is near-universal and gigabit is rolling out. Across the 309 postcodes Ofcom measures in CM21, superfast broadband (30 Mbit/s or faster) reaches 93.8% of premises and gigabit-capable lines are available to 63%.
Around 0.1% of premises in CM21 fall below the Universal Service Obligation (a minimum of 10 Mbit/s download and 1 Mbit/s upload), so the overwhelming majority of homes and businesses here can already order a decent fixed line. For a business that depends on its connection, the figures that matter most are gigabit and full-fibre availability — the symmetric, low-contention services we quote leased lines and FTTP against.
Sample postcodes in CM21
| Postcode | Superfast | Gigabit |
|---|---|---|
| CM21 0AA | 100% | 0% |
| CM21 0AB | 8.7% | 0% |
| CM21 0AD | 94.7% | 0% |
| CM21 0AE | 100% | 0% |
| CM21 0AF | 64.7% | 0% |
| CM21 0AH | 100% | 0% |
| CM21 0AJ | 54.5% | 0% |
| CM21 0AL | 100% | 0% |
| CM21 0AN | 100% | 100% |
| CM21 0AP | 100% | 0% |
Run a speed test to see what you're actually getting, or check your exact postcode.
Mobile signal around East Hertfordshire
Ofcom's coverage model for the wider East Hertfordshire district (71,670 premises):
4G indoors — all networks
87.2%
4G outdoors — all networks
98.8%
5G outdoors — all networks
27.7%
Voice indoors — all networks
90.2%
Signal varies street by street — use the mobile coverage checker to compare EE, O2, Three and Vodafone at an exact postcode.
Crime in CM21
Police recorded 58 incidents within about a mile of the centre of CM21 in May 2026 (latest published street-level data). The breakdown:
| Category | Incidents | Share |
|---|---|---|
| Violence & sexual offences | 21 | 36.2% |
| Anti-social behaviour | 15 | 25.9% |
| Vehicle crime | 5 | 8.6% |
| Public order | 4 | 6.9% |
| Other crime | 4 | 6.9% |
| Burglary | 3 | 5.2% |
| Shoplifting | 2 | 3.4% |
| Bicycle theft | 1 | 1.7% |
Raw counts favour busy town centres — a high street with shops and nightlife records more incidents than a residential cul-de-sac. Source: police.uk open data (point sample around the district centroid).
House prices in CM21
Based on 137 sales registered with HM Land Registry in the last 12 months, the median sold price in CM21 is £425,000, down 10.5% on the previous year (£475,000).
Detached
£602,000
35 sales
Semi-detached
£485,000
34 sales
Terraced
£350,000
32 sales
Flat / maisonette
£221,250
34 sales
Latest recorded sales in CM21
| Date | Price | Type | Street | Postcode |
|---|---|---|---|---|
| 26 May 2026 | £762,500 | Semi-detached | Forebury Avenue | CM21 9BG |
| 8 May 2026 | £147,000 | Flat | Orchard Lea | CM21 0AB |
| 8 May 2026 | £215,000 | Flat | Lawrence Moorings | CM21 9PE |
| 8 May 2026 | £295,000 | Flat | Lawrence Moorings | CM21 9PE |
| 6 May 2026 | £580,000 | Detached | Wheatley Close | CM21 0HS |
| 6 May 2026 | £399,000 | Semi-detached | Springhall Road | CM21 9ET |
| 30 Apr 2026 | £324,000 | Terraced | White Post Field | CM21 0BY |
| 30 Apr 2026 | £520,000 | Semi-detached | Barnard Road | CM21 9DY |
| 30 Apr 2026 | £730,000 | Semi-detached | CM21 0LX | |
| 28 Apr 2026 | £570,000 | Semi-detached | Sheering Mill Lane | CM21 9ND |
Contains HM Land Registry data © Crown copyright and database right 2026, licensed under the Open Government Licence v3.0.
Who lives here? East Hertfordshire demographics
Census 2021 figures for the wider East Hertfordshire district (150,155 residents, 62,023 households):
| Age profile | |
|---|---|
| Under 15 | 19.3% |
| 15–29 | 21.1% |
| 30–44 | 20.5% |
| 45–64 | 20.9% |
| 65+ | 18.2% |
| Housing tenure | |
|---|---|
| Owner-occupied | 69.4% |
| Private rented | 16.1% |
| Social rented | 11.4% |
Source: ONS Census 2021 (district level — the finest openly licensed cut we republish). © Crown copyright, OGL v3.0.
Schools in and around CM21
| School | Phase | Ages | Pupils | Postcode |
|---|---|---|---|---|
| Leventhorpe | Secondary | 11–18 | 1,463 | CM21 9BY |
| Mandeville Primary School | Primary | 3–11 | 318 | CM21 0BL |
| Reedings Junior School | Primary | 7–11 | 243 | CM21 9DD |
| High Wych Church of England Primary School | Primary | 3–11 | 224 | CM21 0JB |
| Fawbert and Barnard Infants' School | Primary | 3–7 | 211 | CM21 9AT |
Source: DfE Get Information about Schools (England & Wales). Check Ofsted report cards for inspection detail — headline one-word grades were retired in 2024.
Food hygiene ratings in CM21
78 rated food businesses operate in CM21. 48 hold the top rating of 5, 13 are rated 4, and 1 are rated 2 or below.
Among the 5-rated: 4T, @phuket Thai Cafe, All Sorts Dementia Group CIC, Barley Barn Sawbridgeworth, Bellwaris Indian Takeaway.
Source: Food Standards Agency, food hygiene ratings (FHRS) open data.
Energy performance (EPC) in CM21
From a sample of 265 Energy Performance Certificates across 12 CM21 postcodes, the most common rating is band B (average band C). 66% of sampled homes are rated C or better.
Band A
1%
Band B
37%
Band C
29%
Band D
23%
Band E
8%
Band F
2%
Source: MHCLG Energy Performance of Buildings Data (England & Wales), sampled at postcode level and refreshed monthly. Individual certificates are on each postcode’s page.
Phone area codes for East Hertfordshire
Landlines around CM21 typically use:
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What's it like living in CM21?
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Moving to CM21? Sort your connectivity first
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Postcodes in CM21
Neighbouring districts
All Chelmsford (CM) postcode districts ›
Frequently asked questions
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Sources: HM Land Registry Price Paid Data, police.uk street-level crime, Ofcom Connected Nations, ONS Census 2021, DfE Get Information about Schools, Food Standards Agency FHRS — all © Crown copyright, licensed under the Open Government Licence v3.0. Figures are area aggregates; individual addresses vary. Energy performance (EPC) data will be added when our Open Data Communities registration is approved.