Riding profile

Portsmouth South

UK constituency — England · Urban · south east

The question

Portsmouth South: a safe seat for Labour?

Editorial read

Portsmouth South, an urban constituency in England, elected a member with Labour in the previous cycle, with a 34-point margin. The Vote-Scope model projects Labour ahead at 34% vote share, against 26% for Reform UK, and the probability of a close race is negligible.

Sitting member

Stephen Morgan

Sits with Labour

Since
2017-06-08
Parliament
59th

Current forecast

Labour

Safe

Probability
100%
Mean margin (pts)
6.5
P(close race)
0%

Projected vote share

Projection by party

  • Labour 34.0%
  • Reform UK 25.8%
  • Lib Dems 15.4%
  • Conservative 11.0%
  • Green 10.7%
  • Other 2.8%

In context

How this riding stacks up

Labour Reform UK Lib Dems Conservative
HerePortsmouth South 34.0%25.8%15.4%11.0%
National averageUnited Kingdom 21.7% +12.4 25.3% +0.5 11.6% +3.7 18.9% −7.9

Nationwide averages computed across the 650 riding-level projections (unweighted mean).

Previous election · UK 2024

Won by
Labour
Margin
33.8 pts
Margin shift vs current projection
-27.2 pts

Detailed result · UK 2024

Candidates and votes

Candidate Party Votes % Occupation
Stephen Morgan Elected Labour 18,857 48.4
Mark Zimmer Reform UK 5,702 14.7
Signe Biddle Conservative 5,643 14.5
Charlie Murphy Lib Dems 4,886 12.6
Elliott Lee Green 3,107 8.0
Jacob Short Other 733 1.9

Demographics

Who lives here

Population
107,571
Median age
33
Employment rate
75.6%

Data source : ONS mid-2022 population + Jan 2026 labour market

Last model run
Cycle
uk_2029