The resignation of Sir Ivan Rogers, the British ambassador to the European Union in Brussels, has raised serious issues not only about Britain's strategy for Brexit but also about relations between officials and politicians and their political advisers.

Rogers was an experienced negotiator and former Treasury official with wide contacts in Europe. He was clearly frustrated by the fact that he was neither adequately consulted nor informed about British aims in the forthcoming negotiations with the EU about Brexit.

He seems to have found the political advisers (Nick Timothy and Fiona Hill) who are the prime minister's chiefs of staff were unwilling to understand the complexities that Britain will face in negotiations with the EU. He was also increasingly frustrated by the apparent obtuseness of the ministers responsible for Brexit, who seemed unable to grasp that the task of persuading the other 27 EU countries to grant Britain a satisfactory deal would be daunting and lengthy.