A leaked British government document regarding preparedness for Brexit, known as Operation Yellowhammer, has indicated that British oil and petrol exports could become “uncompetitive” in European markets if the British side apply zero tariffs and the EU applies higher duties. That could lead to the closure of two British refineries. In the 12 months to Jun. 30 the U.K exported £8.39 billion ($10.17 billion) of refined oil to the EU and imported £8.52 billion. A change in relative competitiveness could therefore have a multi-billion pound effect on the economy. The U.K. may also lose expo...