Cardiff South and Penarth
Wales · Borough constituency
About the Cardiff South and Penarth constituency
Cardiff South and Penarth is a borough constituency in Wales, spanning parts of Cardiff, Vale of Glamorgan and neighbouring councils. The sitting MP is Stephen Doughty (Labour (Co-op)), first elected in November 2012.
At the 2024 general election, Labour won Cardiff South and Penarth with 44.5% of the vote, ahead of the Greens on 14.4%, a majority of 11,767 votes. Turnout was 53.6%.
If a general election were held today, PollCheck's projection at the current seven-poll average has Labour on 26.8% and the Greens on 20.7% in Cardiff South and Penarth, a margin of 6.1 points. The projection updates automatically as new polls are added.
Demographically, Cardiff South and Penarth is a Remain-leaning area (an estimated 42.8% voted Leave in 2016). About 40.8% of residents hold a degree, 51.6% of homes are owner-occupied, and the seat has a median age of about 32 (2021 Census).
Across the most recent general elections on record here, the seat has been won by Labour each time.
Who lives in Cardiff South and Penarth? Constituency demographics
From the 2021 Census and 2016 EU referendum estimates. Constituency-level data on 2024 boundaries.
How did Cardiff South and Penarth vote in 2024 and how would it vote now?
2024 vote shares from the HoC Library. Current projection is at the 7-poll average.
2024 general election
Current projection
Map of Cardiff South and Penarth
Switch between ward-level 2024 election winners and a demographic view. Ward winners are Britain Elects' / New Statesman modelled estimates with an average ~4pp margin of error per ward. The demographic view splits the seat into small neighbourhoods (around 1,500 residents each, from the 2021 Census). Hover any area for detail.
How Cardiff South and Penarth voted at the Senedd election (7 May 2026)
Cardiff South and Penarth sits almost entirely within the Senedd constituency of Caerdydd Penarth. Senedd elections use a closed-list proportional system; each Senedd seat returns six members.
| Senedd constituency | Share of Cardiff South and Penarth | Winner | Runner-up | Seats (6 per constituency) |
|---|---|---|---|---|
| Caerdydd Penarth | 98% | Plaid Cymru 41.0% | Reform UK 17.6% | 3 Plaid Cymru, 1 Reform UK, 1 Green, 1 Labour |
| Caerdydd Ffynnon Taf | 1% | Plaid Cymru 37.0% | Reform UK 19.6% | 3 Plaid Cymru, 1 Reform UK, 1 Labour, 1 Green |
Senedd 2026 results from official declarations. Overlap percentages are area-based using the post-2024 Westminster boundary against the new 16-seat Senedd boundary.
Cardiff South and Penarth within Cardiff and Vale of Glamorgan
Cardiff South and Penarth crosses multiple council boundaries: Cardiff (62%), Vale of Glamorgan (38%). English councils rotate their election cycles and none of the constituent councils were due to vote in 2026, so the figures below show the most recent ward result available for each ward.
Council overlap
| Council | Share of seat |
|---|---|
| Cardiff | 62% |
| Vale of Glamorgan | 38% |
Recent council by-elections
Council ward by-elections held inside this seat, most recent first. The result column shows which party won; the share column shows the top three parties’ vote shares on the day.
| Date | Ward | Result | Top 3 vote shares |
|---|---|---|---|
| 14 Aug 2025 | Grangetown | Grn GAIN from Lab | Grn 24% Lab 23% PC 19% |
| 6 Dec 2024 | Splott | Lab HOLD | — |
| 30 Apr 2024 | Grangetown | Lab HOLD | — |
Most recent council ward results
Latest council winner per ward. Where the council held a May 2026 election, those results are shown; otherwise we show the most recent available ward result (via DCLEAPIL, 2014-2024), or, where the seat was uncontested at the last election, the current sitting councillor from OpenCouncilData. The "Shift since GE2024" column is only computed for May 2026 results - earlier council votes pre-date the GE, so no directional shift is shown.
| Ward | GE2024 winner | Latest council winner | Shift since GE2024 | Turnout |
|---|
Projection trajectory
PollCheck's projection for Cardiff South and Penarth at each of the last 60 GB polls. Hover the chart for the underlying poll details.
Who has won Cardiff South and Penarth at past general elections?
2024 result is on current boundaries. The 2019 row is the UK Parliament's notional recalculation onto the 2024 boundaries (directly comparable to 2024). The 2010, 2015 and 2017 rows are on the boundaries in force at the time and aren't directly comparable.
| Year | Result | MP | Lab | Con | LD | Majority | Turnout |
|---|---|---|---|---|---|---|---|
| 2010 | Lab hold | Alun Michael | 38.9% | 28.3% | 22.3% | 4,709 | 60.2% |
| 2015 | Lab hold | Stephen Doughty | 42.8% | 26.8% | 5.0% | 7,453 | 61.4%+1.2 |
| 2017 | Lab hold | Stephen Doughty | 59.5% | 30.2% | 2.8% | 14,864 | 66.3%+4.9 |
| 2019notional | Labour winner | Stephen Doughty 2019 MP, pre-review boundary | 53.7% | 30.1% | 7.0% | 11,851 | 69.7%+3.4 |
| 2024 | Lab hold | Stephen Doughty | 44.5% | 13.9% | 7.4% | 11,767 | 53.6%-16.1 |
Earlier years are on pre-2024 boundaries; comparable results on the new boundary will be added when sourced.
Constituencies most like Cardiff South and Penarth
Five seats with similar demographic profiles to Cardiff South and Penarth. Politics shown for context.
- ↑Under 3547.7 / 43.4vs 30.2
- ↑Private rent33.2 / 31.7vs 20.2
- ↓Owner-occupied51.6 / 47.9vs 61.9
- ↓Leave42.8 / 37.4vs 53.2
- ↑Under 3547.7 / 40.6vs 30.2
- ↓Owner-occupied51.6 / 54.8vs 61.9
- ↑Under 3547.7 / 45.3vs 30.2
- ↓Leave42.8 / 38.8vs 53.2
- ↓Owner-occupied51.6 / 52.6vs 61.9
- ↑Under 3547.7 / 44.5vs 30.2
- ↑Private rent33.2 / 36.4vs 20.2
- ↓Owner-occupied51.6 / 41.9vs 61.9
- ↑Under 3547.7 / 43.9vs 30.2
- ↓Leave42.8 / 44.8vs 53.2
- ↓Owner-occupied51.6 / 54.0vs 61.9
What would change this seat?
Move the sliders to set national vote shares. The per-seat projection updates live. Reset returns to the current 7-poll average.
Related
Sources
- 2024 general election results · UK Parliament Election Results portal and House of Commons Library briefing CBP-10009.
- Notional 2019 results on 2024 boundaries · UK Parliament Election Results portal. Recalculated by Parliament; carries assumptions about how 2019 voters would have distributed across the redrawn boundaries.
- Historic general election results (2010-2017) · House of Commons Library historic results files (on the boundaries in force at the time).
- Ward-level GE2024 estimates · Britain Elects / New Statesman - article by Ben Walker, underlying spreadsheet. Modelled from constituency totals; average ~4pp per-ward MoE.
- May 2026 council ward results · Democracy Club via PollCheck's locals 2026 dataset.
- Earlier council ward results (2014-2024) · DCLEAPIL v1.0 (Jason Leman, drawing on Andrew Teale's LEAP dataset and Democracy Club).
- Demographics · ONS Census 2021 (England and Wales), aggregated to constituency level using the ONS LSOA21 -> PCON24 best-fit lookup.
- EU referendum 2016 estimates · Constituency-level Leave vote estimates (Hanretty 2017 method).
- MP details and Cabinet roles · UK Parliament Members API. MP photos are fetched live from the same source.
- Boundary geometry and lookups · ONS Open Geography Portal (PCON24 boundaries, LSOA21 boundaries, LSOA21-WD24-LAD24 best-fit lookup).
- Current projection and trajectory · PollCheck's demographic swingometer applied to the rolling 7-poll average from aggregated GB polls. Not a true MRP - vote-share movements are applied through per-constituency sensitivity multipliers derived from demographic regressions.
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