Photo: Roger Cornfoot · CC BY-SA 2.0A median age of 33.8: Trethomas is younger than 97% of UK towns
38% of adults have never married or formed a civil partnership across Wales’s towns, against 46% in Trethomas. There were 707 households in the village at the 2021 Census, home to 1,713 residents. Households in detached houses: 13% of the total. On households without a car or van, Trethomas sits higher than 98% of UK towns: 35%.
What the Census says about Trethomas’s people
A village of families
38% of Trethomas’s 707 households had dependent children in 2021, more than in 97% of UK towns. 25% of residents are under 15. Households ↓
Younger than most towns
Half of Trethomas’s residents are under 33.8 and half over, against 44.4 in the typical UK town. 12% are 15 to 24 and 14% are 65 or over. Ages ↓
More with no religion than most
65% of residents answered “no religion” in 2021 and 28% Christian, against 47% and 43% across Wales’s towns. Ethnicity & religion ↓
Written from the data on this page: ONS Census 2021 (output areas summed to the 2022 built-up area).
A smaller share of residents aged 65 and over than 92% of UK towns: 14%
Share of residents in each five-year age band, Census 2021.
Residents aged 15 to 24 are about as common here as across Wales’s towns, at 12%. On average, 21% of residents are 65 or over across Wales’s towns.
Broad ages · share of residents
Women and men · all residents
53% women, 47% men
About 89 men for every 100 women. Across Wales, 51% of residents are women.
A lower share of residents who moved in within the year than 89% of UK towns, at 6.8%
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%.
Managerial and professional jobs account for 17% of Trethomas’s adults, routine and semi-routine work for 34%, against 29% and 27% across Wales’s towns. As a yardstick, nearly one in ten residents lived at another address a year earlier across Wales’s towns. In Trethomas, 7.3% of adults are full-time students.
The Census was taken on 21 March 2021, in term time, so students were counted at their term addresses.
More households with dependent children than 97% of UK towns: 38%
Household make-up at the 2021 Census. Each square is 1% of households.
Against Gwent’s towns and Wales’s towns
People per household
Wales’s towns.
Shared households of unrelated adults make up 2.7%, close to the figure across Wales’s towns. Average household size: 2.5 people. At 27%, the share of one-person households is lower than in 70% of UK towns.
Trethomas sits above 97% of UK towns for households in terraced houses (48%)
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
Across Wales’s towns, 14% of households live in a flat or apartment; in Trethomas, 7.3%. For households in terraced houses, the comparison across Wales’s towns is 29%.
Below 78% of UK towns: 4% of residents were born outside the UK
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 10%
Main language · residents aged 3 and over
Among residents born abroad, the largest groups were born in EU countries (2.4%) and in the Middle East and Asia (0.6%). As a reference point, 7.4% of residents were born outside the UK across Wales’s towns. Few places have so few residents whose main language is English: 98% here, fewer than in 50% of UK towns.
8.2% of residents speak Welsh in Trethomas
Welsh language skills, residents aged 3 and over, Census 2021.
Welsh language skills · residents aged 3 and over
Welsh speakers number 134, or 8.2% of residents aged 3 and over, against 16% across Welsh towns: fewer than in 85% of them. The highest share in Gwent belongs to Abertridwr and Senghenydd (14%).
Residents with no religion: 65%, a higher share than 99% 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: 95% of Trethomas · Gwent’s towns 91% · Wales’s towns 90%.
Religion · all residents
Set against 43% across Wales’s towns, 28% of residents describe themselves as Christian in Trethomas. Higher than in 82% of UK towns: 95% of residents describe themselves as White British. For comparison, 47% of residents said they have no religion across Wales’s towns. After White British, the largest groups are Other White (2%), Mixed or multiple (1.3%) and Indian (0.2%).
Below 96% of UK towns: 36% of adults are married or in a civil partnership
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
Just over one in ten residents give unpaid care, against 10% across Wales’s towns. By way of comparison, 43% of adults are married or in a civil partnership across Wales’s towns.
Degree-level qualifications: held by 20% of adults
Highest qualification, residents 16 and over, Census 2021.
Highest qualification · residents 16 and over
In Trethomas, 20% of adults hold a degree-level qualification, against 31% across Wales’s towns, while 27% have no qualification at all (20%). Many of the 15% whose highest qualification is A levels are students working towards a degree.
Trethomas is younger than every town around it
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 |
|---|---|---|---|---|---|
| Trethomas | 1,713 | — | 33.8 | 14% | 38% |
| Bedwas | 6,463 | 1.3 mi | 44.4 | 22% | 28% |
| Machen | 1,985 | 1.3 mi | 47 | 22% | 28% |
| Cwmfelinfach | 1,353 | 1.7 mi | 40.4 | 17% | 27% |
| Llanbradach | 3,766 | 2.8 mi | 44.1 | 22% | 25% |
| Caerphilly | 33,104 | 2.9 mi | 42.1 | 20% | 29% |
| Risca | 15,194 | 3 mi | 44.1 | 21% | 26% |
| Abercarn | 5,123 | 4 mi | 40.8 | 18% | 27% |
Health, work and homes have their own pages
What this data can and can’t tell you
- The Census was taken in a lockdown, in term time. 21 March 2021 fell in term time, and students were asked to give their term-time address, so most were counted where they study. Some may have been living with family that day.
- “Gwent’s towns” and “Wales’s towns” mean their built-up areas. Census comparisons pool every built-up area in Gwent (or Wales), summed the same way as Trethomas’s figures, so households in open countryside are left out.
- 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 Trethomas’s residents
What is the population of Trethomas?
The 2021 Census counted 1,713 people in Trethomas’s built-up area.
What is the average age in Trethomas?
The median age was 33.8 at the 2021 Census. 12% of residents were 15 to 24 and 14% were 65 or over.
How diverse is Trethomas?
95% of residents described themselves as White British in 2021, against 90% across Wales’s towns and 91% across Gwent’s towns. 4% were born outside the UK.
What religion are people in Trethomas?
65% said they had no religion and 28% that they were Christian at the 2021 Census; 0% were Muslim and 5.1% didn’t answer.
Is Trethomas good for families?
38% of households had dependent children in 2021, against 27% across Wales’s towns. Schools are on Trethomas’s schools page.
How many people speak Welsh in Trethomas?
134 residents aged 3 and over, 8.2%, said they can speak Welsh at the 2021 Census, against 16% across Welsh towns.
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, TS032). 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.