The head of the World Trade Organisation (WTO) said today it would not be "the end of the world" if Britain failed to reach a post-Brexit trade deal with the EU, but there would be costs. <br/><br/>Roberto Azevedo told a British daily that although Britain would be better off with an agreement, the impact of falling back on WTO rules would be manageable. <br/><br/>He said that about half of the UK's trade is already on WTO terms — with the US, China and several large emerging nations where the EU doesn't have trade agreements.<br/>'<br/>Britain intends to leave the EU's single market and customs union when it withdraws from the bloc in March 2019, but hopes to reach a free trade agreement with Brussels before then.<br/>'<br/>However, trade talks have yet to formally start, and without a deal, bilateral trade would likely be subject to higher WTO tariffs as well as other barriers such as increased red tape.<br/>