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The evidence centre

Every number, and where it comes from

The full evidence base behind this campaign: the charts, the sources they trace to, and a linked library of the underlying research. Where a figure cannot be traced to a specific document, we remove it rather than publish it.

The charts

The evidence in charts

Cash trade figures keep rising with inflation and growth, so they hide the real story. The honest question is the counterfactual: how has the UK done compared with where it would otherwise have been — and compared with similar economies? Every chart states its method and links to its source.

The OBR's central long-term Brexit assumptions

The Office for Budget Responsibility's central assumptions, compared with remaining in the EU. The productivity effect is assumed to build over roughly 15 years.

0%UK exports−15%UK imports−15%Potential productivity−4%
Source: OBR, Brexit analysis (Forecasts in-depth) · Method: long-run counterfactual assumptions used in official forecasts

One recent research estimate of Brexit's economic impact by 2025

Estimated effects relative to where the economy might otherwise have been — not literal falls since 2016. Darker bars show the lower estimate; lighter extensions the upper.

0%GDP−6% to −8%Business investment−12% to −18%Employment−3% to −4%Productivity−3% to −4%
Source: Swati Dhingra, “Tariffed with the same brush”, Bank of England speech, 22 October 2025, citing Bloom et al., “The Economic Impact of Brexit”, NBER Working Paper 34459 · Method: research estimates presented in a speech — modelled counterfactuals shown as ranges, not an official Bank of England forecast

Britain's goods trade recovery has lagged the G7

Goods trade volumes, indexed to 2019 = 100. UK figures are for the end of 2023; rest-of-G7 comparisons use the latest 2023 observations cited by the OBR.

Goods trade volumes · index: 2019 = 1008590951001051102019End of 2023Rest of G7 average: 105United Kingdom: 90
Source: OBR, “How are our Brexit trade forecast assumptions performing?”, EFO Box, March 2024 · Method: relative recovery since 2019; volume indices, not cash values

UK trade intensity fell while the G7's rose

Percentage change in trade intensity since 2019. Trade intensity means exports plus imports as a share of GDP.

Change in trade intensity since 2019United Kingdom−1.7%Rest of G7 average+1.7%
Source: OBR, EFO Box, March 2024 (OECD and ONS data) · Method: observed percentage change relative to 2019

UK–EU goods trade grew far more slowly than the EU's other goods trade, 2019–2022

Growth in current prices, 2019–2022 — not inflation-adjusted. Figures are approximate published values and labelled as such.

Trade within the EU, and betweenthe EU and the rest of the worldMore than 33%UK–EU goods tradeAround 10%
Source: OBR, Brexit analysis (Forecasts in-depth) · Method: current-price comparison reported by the OBR; the benchmark combines trade between EU countries and EU trade with non-UK countries

Goods bore the brunt of the new trade barriers

Change in trade volumes since 2019. UK figures are for the end of 2023; rest-of-G7 figures are the latest 2023 observations cited by the OBR. UK services kept pace — UK goods went the other way.

-15%-10%-5%0%+5%+10%+15%-10%UK goods+5%G7 goods+12%UK services+9%G7 services
Source: OBR, “How are our Brexit trade forecast assumptions performing?”, EFO Box, March 2024 · Method: observed volume changes relative to 2019

The market at a glance

30countries formally in the Single Market — the EU 27 plus Iceland, Liechtenstein and Norway
450mconsumers in the world's largest integrated market
26mbusinesses trading under common rules
€18tncombined GDP of the market
3–4%the Commission's estimate of the boost to EU GDP since 1993
3.6mjobs the Commission estimates the market has created

Scale figures: European Commission · formal 30-country definition: Council of the EU infographic. Switzerland participates in substantial parts of the market through bilateral agreements but is not part of the formal 30-country total. All impact figures above are estimates or modelled counterfactuals, clearly distinct from direct observations.

Claim by claim

Where our numbers come from

The key figures used across this site, each linked to the source document it comes from — tagged as official statistic, forecast assumption, or research estimate.

~450 million consumers; 26 million businesses; €18tn GDP; the world's largest integrated trading area Official statistic
European Commission, “Single market” — facts and figures; Council of the EU, “30 years of the EU single market” infographic (2023)
Member economies around 8–9% larger due to the Single Market Academic estimate
Jan in 't Veld, “Quantifying the Economic Effects of the Single Market in a Structural Macromodel”, European Commission Discussion Paper 094, February 2019 — total estimate of around 9% higher GDP on average for the EU
UK long-run productivity ~4% lower and trade intensity ~15% lower outside the market Official forecast assumption
Office for Budget Responsibility, “Brexit analysis”, Forecasts in-depth (updated March 2025) — effect assumed to build over roughly 15 years
UK vs G7 trade figures in the charts above Official analysis of observed data
OBR, “How are our Brexit trade forecast assumptions performing?”, Economic and Fiscal Outlook Box, March 2024 — based on OECD and ONS data
Around £250 added to average household food bills (Dec 2019 – Mar 2023) by new trade barriers Academic estimate
Bakker, Datta, De Lyon et al., “Brexit and consumer food prices: May 2023 update”, LSE Centre for Economic Performance, Brexit Analysis No. 18 — £250 per household, £6.95bn overall
Business investment below its pre-referendum path Research & think-tank models
Bank of England: Dhingra speech, October 2025; Centre for European Reform, “Cost of Brexit” doppelgänger series (Springford)
GDP, investment and employment estimates in the research chart above Research estimate
Swati Dhingra, “Tariffed with the same brush”, Bank of England speech, 22 October 2025, citing Bloom et al., NBER Working Paper 34459 — not an official Bank forecast
EEA, EFTA and treaty facts throughout Official treaty texts
EFTA Secretariat; the EEA Agreement and EFTA Convention texts; UK Parliament research briefings
Go deeper

The research library

The primary documents behind this site, in one place. All links open the original publishers.

OBR — Brexit analysis (Forecasts in-depth) Official forecast
The Office for Budget Responsibility's standing page on its Brexit assumptions: 15% lower trade intensity, 4% lower long-run productivity, built over ~15 years.
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OBR — “How are our Brexit trade forecast assumptions performing?” (EFO Box, March 2024) Official analysis
The source of the UK-vs-G7 goods, services and trade-intensity comparisons in our charts. Based on OECD and ONS data.
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Dhingra — “Tariffed with the same brush” (Bank of England speech, October 2025) Research estimate
MPC member Swati Dhingra's summary of the research evidence: GDP 6–8% lower, investment 12–18% lower, employment and productivity 3–4% lower.
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Bloom et al. — “The Economic Impact of Brexit” (NBER Working Paper 34459) Academic paper
The published academic study behind those estimates, combining firm-level and macroeconomic evidence.
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in 't Veld — “Quantifying the Economic Effects of the Single Market” (European Commission, 2019) Academic estimate
The Commission's structural-model estimate that the Single Market leaves member economies around 9% larger on average.
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LSE CEP — “Brexit and consumer food prices: May 2023 update” (Brexit Analysis No. 18) Academic estimate
Bakker, Datta, De Lyon et al.: new trade barriers added around £250 to the average household's food bills between December 2019 and March 2023 — about £7bn overall.
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Centre for European Reform — “Cost of Brexit” series Think-tank model
John Springford's doppelgänger model tracking the gap between the UK economy and a data-matched counterfactual.
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Federal Trust — “The Economic Impact of Brexit, Nine Years On” (January 2026) Research report
Springford's full audit of the published evidence, nine years after the referendum.
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House of Commons Library — “The 2026 review of the UK–EU Trade and Cooperation Agreement” Parliamentary briefing
Parliament's neutral briefing on the TCA review and the state of the reset negotiations.
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European Commission — “Single market” topic page Official statistic
The official facts and figures: 30 countries, ~450 million consumers, 26 million businesses, €18tn GDP.
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Council of the EU — “30 years of the EU single market” infographic Official reference
The formal definition of the 30-country market and the four freedoms, marking the 1993–2023 anniversary.
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EFTA Secretariat — the EEA Agreement and EFTA Convention Treaty texts
The treaty texts behind everything this site says about the EEA and EFTA.
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This library will grow — downloadable briefings, trade statistics and our own published research will live here. Suggest an addition: info@singlemarketmatters.uk.

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