If the UK leaves the European Union without a deal, Britain would begin trading under World Trade Organisation rules - but what are they?

David Henig of the European Centre for International Political Economy who was also involved in discussions about the Transatlantic Trade and Investment Partnership, says: "Think of it as the basics of trade rules between two countries.

"They set basic tariffs for between countries, the basic levels of market access that all members agree to give each other and a fairly loose framework of rules to say you can't discriminate against others. You've got to play reasonably fair on state aid, you've got to have reasonably fair regulations with regard to agriculture."