What happened
The World Trade Organization sets the minimum terms on which member countries trade with each other. Under WTO 'Most Favoured Nation' (MFN) rules, every country must offer all other WTO members the same basic tariff rate — it cannot give the UK a better deal than it gives anyone else unless there is a separate trade agreement.
This means that trading 'on WTO rules' without any deal is not a neutral baseline — it is the worst possible tariff arrangement the EU can legally offer. The rates UK exporters would face under pure WTO MFN: • Cars: 10% tariff (against 0% under the single market) • Vans: 6.5% • Beef: 12.8% + specific duties • Lamb: 12.8% + €1.11/kg • Chicken: 32.5% • Cheese: 40% + specific duties • Fish: 8–20% depending on species
These are not trivial numbers. A 10% tariff on every car exported to the EU would have made British-made cars uncompetitive and likely closed plants in Sunderland, Swindon, and Ellesmere Port. UK agriculture — already operating on thin margins — would have faced continental competition with no tariff barrier at all while losing free access to the EU.
But the tariff problem, while serious, is not even the main problem. The main problem is this:
**WTO rules do not cover services.**
The UK's economy is approximately 80% services. Financial services, legal services, consulting, accountancy, architecture, advertising, data processing — none of these are covered by WTO frameworks for market access. There is no WTO 'passporting'. There is no WTO mechanism by which a UK bank can offer services in Frankfurt, a UK lawyer can practise in Paris, or a UK accountant can audit a company in Amsterdam.
The City of London's financial services industry operated under EU 'passporting' — a right to sell services across all 27 EU member states without a separate licence in each country. Under WTO rules, that right disappears entirely. Each UK financial firm would need to obtain licences in each EU country individually, or establish a subsidiary inside the EU. Many did: JPMorgan moved operations to Dublin, Goldman Sachs to Frankfurt, Deutsche Bank consolidated in Frankfurt, Citigroup established EU headquarters in Dublin. The departure of financial operations from London to EU cities was a direct consequence of what WTO rules actually mean for services.
Additionally, WTO rules don't just 'apply' automatically — the UK had to negotiate its own goods schedule when it left the EU's schedule. The EU immediately challenged whether the UK could simply inherit the EU's tariff rate quotas (TRQs — the amounts of specific products that can be imported at lower tariffs). This dispute took years to resolve.
Finally, there is the 'rules of origin' problem. Under WTO MFN, goods need to qualify as originating in the exporting country to benefit from the tariff arrangement. A car assembled at Nissan Sunderland from components sourced from across the EU might not qualify as 'UK origin' if the percentage of UK-origin content falls below a threshold — which for cars under a WTO-only arrangement would result in an additional tariff on top of the 10%.
**The politicians who said this was fine:**
• *Jacob Rees-Mogg*: Claimed '90% of world trade is done on WTO terms' — a statistical sleight of hand that conflates countries participating in the WTO with trade happening without bilateral agreements. In reality, virtually no significant trade relationship operates purely on WTO MFN without any supplementary deal.
• *Steve Baker* (ERG chair): Called no-deal 'perfectly logical' and WTO rules 'perfectly serviceable'. He said this without addressing services, without addressing financial passporting, without addressing tariff schedules.
• *Liam Fox* (International Trade Secretary): Promised 'the easiest trade deals in the history of mankind'. The UK-US trade deal, which Fox predicted would be ready immediately, still did not exist in 2026.
• *Boris Johnson*: Said Turkey was doing 'fantastically well' trading with the EU on WTO terms. Turkey has a customs union with the EU — it is the opposite of WTO-only trading.
• *David Davis*: Said a comprehensive deal would be ready 'within the first year or two'. He resigned before one was reached.
WTO rules were not a plan. They were a threat — a way of saying 'we'll walk away' without having to explain to anyone what walking away actually meant. The people who deployed this threat either did not understand what it meant or did not care. In either case, they were not fit to be making the decision.