What is Opinium Research?

Opinium Research is the official polling partner of The Observer newspaper and one of the most active UK pollsters, publishing voting intention approximately weekly. Founded in 2008, the independently owned firm uses online panel methodology with 2,000-respondent standard surveys published every Saturday in The Observer.

How accurate was Opinium at the 2024 general election?

Opinium was among the best-performing pollsters at the 2024 General Election with a mean absolute error of 2.8 percentage points — second only to YouGov. Their final poll showed Labour at 36%, Conservatives at 22%, Reform UK at 13%, and Lib Dems at 13%, against actual results of Lab 33.7%, Con 23.7%, Reform 14.3%, LD 12.2%.

What methodology does Opinium use?

Opinium conducts all voting intention polling online using its proprietary panel. Standard surveys achieve exactly 2,000 interviews (margin of error approximately plus or minus 2.2%). Weights are applied for age, gender, region, social grade, and 2024 vote recall. Fieldwork runs Wednesday to Friday for Saturday Observer publication.

What is Opinium's current voting intention for UK parties?

Opinium's most recent voting intention (May 2026) shows Reform UK at approximately 28%, Labour at 19%, Conservatives at 18%, Liberal Democrats at 22%, and Greens at 9%. Opinium publishes weekly voting intention polls for The Observer newspaper, making them one of the more frequent publishers in the industry. Their results are broadly consistent with the polling average, with Reform UK figures slightly above the consensus — a pattern that has been consistent across their recent polling.

How accurate was Opinium at the 2024 general election and previous elections?

Opinium's final 2024 poll showed Labour on 39%, Conservatives on 22%, Reform on 14%, and Lib Dems on 12%. The Labour overestimate of 5 points was in the middle of the industry range. In 2019, Opinium was broadly accurate on Conservative support. Their methodology uses online panel sampling with specific demographic and past-vote weighting. They are known for their consistency in methodology across election cycles, which makes their trend data particularly reliable for tracking poll movements even if absolute figures have some systematic bias.

What is Opinium's typical weekly publication schedule?

Opinium publishes voting intention polls weekly for The Observer (Sunday), making them one of the highest-frequency trackers in the UK polling market. Their weekly data provides a near-real-time view of political movement, with polls typically fielded in the first half of the week and published on Friday-Saturday ahead of the Sunday newspaper. This frequency means individual Opinium polls are less likely to be treated as definitive news events than those from monthly publishers, but their cumulative trend data is particularly valuable for tracking week-to-week movement.

Pollster Profile

Opinium Research: Observer Poll & UK Voting Intention

Last updated: May 2026 — BritPolls Editorial

Opinium Research is a full-service market research firm best known in political circles as the official polling partner of The Observer — the Sunday newspaper published alongside The Guardian. The partnership, running for over a decade, gives Opinium one of the most prominent platforms in UK political polling: Observer-Opinium polls are published on Saturday evenings each week, typically setting the political agenda for the coming week.

Opinium was founded in 2008 and has grown to become one of the UK larger independent research agencies. Unlike some rivals that are subsidiaries of large global research corporations, Opinium remains independently owned — a factor that some political clients consider an advantage when commissioning sensitive research.

Opinium methodology

Opinium conducts all its voting intention polling online, using its proprietary panel. The standard voting intention survey achieves exactly 2,000 completed interviews — a deliberate choice maintained consistently, giving a standard statistical margin of error of approximately plus or minus 2.2 percentage points at the 95% confidence level.

Panel management: Opinium recruits panel members through online advertising, social media, and partner recruitment networks. Panel members are paid per completed survey, which Opinium argues provides better engagement than points-based systems.
Sample design: Interlocking age-gender-region quotas ensure the raw sample broadly reflects the British adult population before weighting. Social grade quotas are also applied at the sampling stage.
Fieldwork timing: Observer-Opinium polls run Wednesday to Friday, enabling publication in the Saturday paper. This three-day fieldwork window produces consistent turnaround.
Weighting: Weights are applied for age, gender, region, social grade, and 2024 General Election vote recall. Opinium uses a conservative vote recall weight, applying a small correction for the known tendency of voters to claim they voted for the winning party.
Voting intention question: Standard BPC-approved wording. Respondents who say they are undecided are offered a follow-up squeeze question asking which party they would be most likely to support. Squeezed leaners are counted as a half-weight contribution to the headline figures.

Opinium May 2026 voting intention

Labour

27%

Reform UK

26%

Conservatives

22%

Lib Dems

13%

Greens

Opinium for The Observer, fieldwork 7–9 May 2026. n=2,000.

Recent Opinium polls: 2025–2026

Date	Lab	Con	Reform	LD	Grn	n
9 May 2026	27%	22%	26%	13%	7%	2,000
2 May 2026	27%	22%	26%	14%	6%	2,000
25 Apr 2026	28%	22%	25%	14%	6%	2,000
18 Apr 2026	28%	23%	25%	13%	7%	2,000
11 Apr 2026	28%	23%	24%	13%	6%	2,000
28 Mar 2026	29%	24%	23%	13%	6%	2,000

The Observer partnership

The Observer-Opinium partnership is one of the most consistent media-pollster relationships in UK journalism. The Observer has published Opinium voting intention data on an approximately weekly basis since 2013, giving the dataset a continuous run of over twelve years. This long consistent series allows genuine like-for-like comparisons of party support across time without methodological changes distorting the trend. The Observer typically publishes Opinium headline figures in its Saturday edition. Full data tables are published on the Observer and Opinium websites and deposited with the BPC archive.

Opinium accuracy at GE2024

At the 2024 General Election, Opinium was one of the better-performing pollsters. Its final poll showed Labour at 36%, Conservatives at 22%, Reform UK at 13%, and the Liberal Democrats at 13%. Against the actual result (Lab 33.7%, Con 23.7%, Reform 14.3%, LD 12.2%), Opinium mean absolute error was 2.8 points — second only to YouGov in the industry ranking. The firm overstated Labour by 2.3 points, understated Reform by 1.3 points, and was essentially spot-on for the Liberal Democrats. See the full accuracy table for all pollsters and elections.

Opinium clientele beyond The Observer

While The Observer partnership is Opinium’s most visible platform, the firm conducts significant polling for a wider range of clients. These include Sky News, for which Opinium conducts occasional voting intention surveys and issue polling; financial services firms and trade bodies tracking public attitudes to economic policy; and various think tanks and campaigning organisations. Opinium’s independence — as a privately owned firm without a corporate parent — is a factor some clients value when commissioning sensitive political research. The firm is a full member of the British Polling Council and publishes full data tables with every voting intention release. Cross-tabs showing results by age, region, and 2024 vote recall are available for download on the Opinium website and BPC archive.

Opinium in the 2024 and 2025 landscape

Opinium was one of the better performers at the 2024 General Election, with a mean absolute error of 2.8 percentage points — second only to YouGov in the accuracy rankings. Since 2024, the firm has continued its Observer partnership and expanded its tracker coverage to include leader approval ratings, issue salience, and economic sentiment questions alongside voting intention. Their treatment of the Reform UK surge has been broadly in line with the cross-firm consensus, neither significantly over- nor under-estimating Reform’s rise from 14% in July 2024 to approximately 26% by May 2026. For a full comparison of how Opinium figures align with the cross-firm average, see the voting intention tracker and our house effects page.

Opinium house effects

Opinium sits close to YouGov in the polling distribution. The two firms typically produce similar Labour and Conservative figures. Reform UK is marginally lower with Opinium than YouGov on average (roughly 1 point). The Lib Dem figures are nearly identical between the two firms. Opinium Green Party figures are slightly higher than the cross-firm average, possibly reflecting the slightly younger skew of the Observer readership. For the full house-effect analysis including Opinium adjustment factors, see the house effects explainer.