30 Most Marginal Seats 2029
Ranked by projected MRP majority — the knife-edge constituencies that will be called last on election night.
Top 10 Closest Seats — Chart
May 2026 MRPAll 30 Most Marginal Seats
| Rank | Constituency | Region | Projected Winner | Winner % | Runner-up | Runner-up % | Margin | Battle |
|---|---|---|---|---|---|---|---|---|
| #1 | Wentworth & Dearne | Yorkshire | Reform | 34% | Labour | 33% | 1% | Lab-Reform |
| #2 | Isle of Wight East | South East | Reform | 33% | Con | 32% | 1% | Con-Reform |
| #3 | Derbyshire Dales | East Midlands | Lib Dem | 34% | Con | 33% | 1% | Con-Lib Dem |
| #4 | Rother Valley | Yorkshire | Reform | 38% | Labour | 36% | 2% | Lab-Reform |
| #5 | Don Valley | Yorkshire | Reform | 37% | Labour | 35% | 2% | Lab-Reform |
| #6 | Barnsley South | Yorkshire | Reform | 35% | Labour | 33% | 2% | Lab-Reform |
| #7 | Mexborough & Dearne Valley | Yorkshire | Reform | 36% | Labour | 34% | 2% | Lab-Reform |
| #8 | Mansfield | East Midlands | Reform | 34% | Labour | 32% | 2% | Lab-Reform |
| #9 | NW Leicestershire | East Midlands | Reform | 33% | Labour | 31% | 2% | Lab-Reform |
| #10 | Guildford | South East | Lib Dem | 35% | Con | 32% | 3% | Con-Lib Dem |
| #11 | Hartlepool | North East | Reform | 36% | Labour | 33% | 3% | Lab-Reform |
| #12 | Stoke-on-Trent North | West Midlands | Reform | 35% | Labour | 32% | 3% | Lab-Reform |
| #13 | S Basildon & E Thurrock | East of England | Reform | 36% | Labour | 32% | 4% | Lab-Reform |
| #14 | Thurrock | East of England | Reform | 35% | Labour | 31% | 4% | Lab-Reform |
| #15 | Ashfield | East Midlands | Reform | 35% | Labour | 30% | 5% | Lab-Reform |
| #16 | Hemel Hempstead | East of England | Reform | 34% | Labour | 29% | 5% | Lab-Reform |
| #17 | South West Surrey | South East | Lib Dem | 36% | Con | 30% | 6% | Con-Lib Dem |
| #18 | Doncaster East & IoA | Yorkshire | Reform | 35% | Labour | 29% | 6% | Lab-Reform |
| #19 | Great Yarmouth | East of England | Reform | 38% | Con | 31% | 7% | Con-Reform |
| #20 | Stoke-on-Trent Central | West Midlands | Reform | 34% | Labour | 27% | 7% | Lab-Reform |
| #21 | Louth & Horncastle | East Midlands | Reform | 38% | Con | 30% | 8% | Con-Reform |
| #22 | Sittingbourne & Sheppey | South East | Reform | 37% | Con | 29% | 8% | Con-Reform |
| #23 | Wigan | North West | Reform | 33% | Labour | 25% | 8% | Lab-Reform |
| #24 | Winchester | South East | Lib Dem | 38% | Labour | 28% | 10% | Lab-Lib Dem |
| #25 | Boston & Skegness | East Midlands | Reform | 42% | Con | 32% | 10% | Con-Reform |
| #26 | Basingstoke | South East | Lib Dem | 33% | Con | 23% | 10% | Con-Lib Dem |
| #27 | Cannock Chase | West Midlands | Reform | 36% | Labour | 26% | 10% | Lab-Reform |
| #28 | Mid Bedfordshire | East of England | Reform | 35% | Con | 25% | 10% | Con-Reform |
| #29 | Barnsley North | Yorkshire | Reform | 34% | Labour | 24% | 10% | Lab-Reform |
| #30 | Dover & Deal | South East | Reform | 34% | Con | 24% | 10% | Con-Reform |
Margins shown in MRP percentage points. Red = under 2pts, amber = 3-5pts, green = 6-10pts. Source: UKPollingData MRP model, May 2026.
Regional Breakdown
Yorkshire — 7 seats
South Yorkshire dominates the marginals list. The post-industrial belt from Barnsley to Doncaster shows some of the most dramatic shifts in British electoral history — seats Labour held for decades now genuinely competitive for Reform UK.
East of England — 5 seats
Essex and the eastern counties feature heavily in the Con-Reform battle. Seats like Thurrock and South Basildon were already marginal; Reform's rise has made them knife-edge contests again.
South East — 6 seats
A mixed bag: Reform vs Conservatives on the Kent coast, Lib Dems vs Conservatives in Surrey and Hampshire. The South East hosts two entirely different electoral battles happening simultaneously.