Primrose Cottage · Photo: Geoff Holland · CC BY-SA 2.0Seaton Sluice is older than 97% of UK towns: a median age of 55.4
Set against 21% across England’s towns, 7.7% of households live in a detached house in Seaton Sluice. The town counted 2,957 residents and 1,439 households at the 2021 Census. Census figures put shared households of unrelated adults at 1.3% locally. 57% of residents describe themselves as Christian, more than in 88% of UK towns.
What the Census says about Seaton Sluice’s people
Older than most towns
Half of Seaton Sluice’s residents are under 55.4 and half over, against 44.4 in the typical UK town. 34% are 65 or over, against 18% across England’s towns. Ages ↓
Fewer people than in 2011
ONS mid-year estimates put Seaton Sluice at 3,100 in 2011 and 2,900 in 2024, down 7%, against 10% for England: slower growth than in 99% of UK towns. Since 2011 ↓
Written from the data on this page: ONS Census 2021 (output areas summed to the 2022 built-up area) and ONS mid-year population estimates.
Since 2011, Seaton Sluice has changed by −7%, slower than 99% of UK towns
ONS mid-year estimates, each year indexed to mid-2011 = 100. Seaton Sluice’s figure is the small areas (2021 LSOAs) that make up the town.
People, mid-2011 = 100
Change by age, 2011 to 2024
About 3,100 people in 2011; 2,900 in 2024.
The 65 and over age group moved most (+13%); the 0 to 15 group moved least (−24%).
More residents aged 65 and over than 96% of UK towns: 34%
Share of residents in each five-year age band, Census 2021.
Across England’s towns, 12% of residents are aged 15 to 24; in Seaton Sluice, 7.5%. Elsewhere, 18% of residents are 65 or over across England’s towns.
Median age of UK towns of 2,500+
■ Seaton Sluice, 55.4. The typical town is 44.4.
Broad ages · share of residents
Women and men · all residents
52% women, 48% men
About 91 men for every 100 women. Across England, 51% of residents are women. Women live longer than men, so towns with many older residents have more women.
7.1% of residents lived at another address a year earlier, fewer than in 83% of UK towns
What adults did at the 2021 Census (the ONS’s NS-SEC classes), and where residents lived a year earlier.
Adults by occupation class · residents 16 and over
Address a year before the Census
Residents who lived somewhere else a year earlier. The bar runs to 25%.
Set against 7.9% across England’s towns, 4.2% of adults are full-time students in Seaton Sluice. The share of residents who moved in within the year across England’s towns is 11%.
18% of households have dependent children, below 97% of UK towns
Household make-up at the 2021 Census. Each square is 1% of households.
Against Northumberland’s towns and England’s towns
People per household
England’s towns.
The average household has 2 people, against 2.4 across England’s towns. For Seaton Sluice, the census puts one-person households at 35%. Elsewhere, 29% of households have dependent children across England’s towns.
A larger share of households without a car or van than 67% of UK towns: 19%
Accommodation type and cars or vans per household, Census 2021. Owning and renting are on Cost of living.
Type of home
Cars or vans · share of households
Nearly a quarter of households live in a terraced house across England’s towns, against 17% in Seaton Sluice. On the census count, just over one in ten households live in a flat or apartment.
Seaton Sluice ranks below 95% of UK towns on residents born outside the UK: 2.6%
Country of birth, year of arrival and main language, Census 2021.
Born outside the UK, by region · share of all residents; the bar runs to 25%
Main language · residents aged 3 and over
99% of residents have English as their main language (England’s towns: 90%). The benchmark for residents born outside the UK across England’s towns: 18%. The largest groups were born in EU countries (1%) and in Africa (0.6%).
Residents who describe themselves as White British: 97%, a higher share than 98% of UK towns
How residents described themselves at the 2021 Census. Lines join the lowest and highest of the three figures.
Ethnic groups other than White British · all residents
White British, not charted: 97% of Seaton Sluice · Northumberland’s towns 96% · England’s towns 73%.
Religion · all residents
At 37%, the share of residents with no religion is in line with the figure across England’s towns. By way of comparison, 73% of residents describe themselves as White British across England’s towns.
Seaton Sluice ranks below 94% of UK towns on adults who have never married: 25%
Legal partnership status (residents 16 and over) and unpaid care (residents 5 and over), Census 2021.
Partnership status · residents 16 and over
Unpaid care given · share of residents 5 and over
Unpaid care takes 50 hours a week or more for 90 people. 52% of adults are married or in a civil partnership, a higher share than in 77% of UK towns. The comparison figure for adults who have never married is 39% across England’s towns. Little separates the share of unpaid carers here, 9.4%, from the figure across England’s towns.
The share of adults with a degree-level qualification: 31%
Highest qualification, residents 16 and over, Census 2021.
Highest qualification · residents 16 and over
With 31% of its adults qualified to degree level, Seaton Sluice compares with 34% across England’s towns; another 17% hold no qualification (18%).
Among 514 UK towns of 2,500 to 4,000 people, the 28th oldest
Median age, Census 2021. Hover a dot for its students and residents born abroad; click for its page.
The youngest is Keele (20.6) and the oldest West Chiltington (63.1). Nearest to Seaton Sluice in age: Cowbridge (54.8), Brockenhurst (55.1), Nettleham (55.4) and Mere (55.4).
No nearby town is as old as Seaton Sluice
Nearby built-up areas coloured by median age, Census 2021. Tap a town for its page.
| Town | People | Away | Median age | 65+ | Homes with children |
|---|---|---|---|---|---|
| Seaton Sluice | 2,957 | — | 55.4 | 34% | 18% |
| New Hartley | 1,764 | 1.9 mi | 46.8 | 22% | 28% |
| Seaton Delaval | 8,012 | 2 mi | 46.5 | 23% | 22% |
| Whitley Bay | 36,876 | 2.6 mi | 46.6 | 24% | 29% |
| Seghill | 2,799 | 3.2 mi | 48.2 | 25% | 20% |
| Blyth | 39,731 | 3.3 mi | 41.6 | 20% | 27% |
| Shiremoor | 6,965 | 3.4 mi | 38.4 | 16% | 31% |
| Backworth | 4,483 | 3.8 mi | 36 | 9.8% | 39% |
Health, work and homes have their own pages
What this data can and can’t tell you
- “Northumberland’s towns” and “England’s towns” mean their built-up areas. Census comparisons pool every built-up area in Northumberland (or England), summed the same way as Seaton Sluice’s figures, so households in open countryside are left out. The population trend compares with the whole county and nation.
- Estimates since 2021 are modelled. The ONS builds mid-year estimates from the Census, births, deaths and migration records. Seaton Sluice’s trend uses the small areas (2021 LSOAs) with most of their people inside it: 2,957 people in 2021, against 2,957 in the built-up area.
- Small counts are blurred. The ONS adds small random changes to Census counts to protect privacy, so the same total differs a little between tables, and the shares of a small town can move by a point or two.
Questions about Seaton Sluice’s residents
What is the population of Seaton Sluice?
The 2021 Census counted 2,957 people in Seaton Sluice’s built-up area. The ONS estimates the same small areas held 2,900 people in mid-2024, 7% fewer than in 2011.
What is the average age in Seaton Sluice?
The median age was 55.4 at the 2021 Census, older than 97% of UK towns. 7.5% of residents were 15 to 24 and 34% were 65 or over.
How diverse is Seaton Sluice?
97% of residents described themselves as White British in 2021, against 73% across England’s towns and 96% across Northumberland’s towns. 2.6% were born outside the UK.
What religion are people in Seaton Sluice?
37% said they had no religion and 57% that they were Christian at the 2021 Census; 0.3% were Muslim and 5.1% didn’t answer.
Is Seaton Sluice good for families?
18% of households had dependent children in 2021, against 29% across England’s towns. Schools are on Seaton Sluice’s schools page.
Sources: ONS Census 2021, output areas summed to the ONS 2022 built-up area (TS002, TS003, TS004, TS007A, TS008, TS015, TS017, TS019, TS021, TS029, TS030, TS039, TS044, TS045, TS062, TS067) · ONS mid-year population estimates for 2021 LSOAs, mid-2011 to mid-2024. All under the Open Government Licence v3.0.
Contains public sector information licensed under the Open Government Licence v3.0. Contains HM Land Registry data © Crown copyright and database right 2026. Contains OS data © Crown copyright and database right 2026 (ONS boundaries). Northern Ireland: Source: NISRA; contains Land & Property Services data and Ordnance Survey of Northern Ireland information, © Crown copyright, licensed under the Open Government Licence v3.0. Scotland: contains National Records of Scotland data, Registers of Scotland data and SEPA data, © Crown copyright / © SEPA 2025, licensed under the Open Government Licence v3.0.