Barnier, a  former vice-president of the European Commission and former French minister, held the post of EU commissioner for internal markets and services between 2010 and 2014. In this capacity he oversaw the development of new regulations on statutory audit, which include mandatory auditor rotation and limitations on the supply of non-audit services.  He was also a key figure in the introduction of tighter banking controls.

In his new role, Barnier will report directly to the president of the European Commission, Jean-Claude Juncker.  He will be advised by a group of directors-general dealing with the issues relevant to the negotiations. He takes up his duties on 1 October 2016.

Juncker said: ‘Michel is a skilled negotiator with rich experience in major policy areas relevant to the negotiations, namely as minister for foreign affairs and for agriculture, and as member of the commission, in charge of regional policy, institutional reforms and of internal market and services.

‘Michel will have access to all Commission resources necessary to perform his tasks. He will report directly to me, and I will invite him to brief regularly the college to keep my team abreast of the negotiations. I am sure that he will live up to this new challenge and help us to develop a new partnership with the UK after it will have left the EU.’

In line with the principle of 'no negotiation without notification', the task of the chief negotiator in the coming months will be to prepare the ground internally for the work ahead. Once the Article 50 process is triggered, which marks the start of the legal process for withdrawal, he will take the necessary contacts with the UK authorities and all other EU and member state interlocutors.

A UK government spokesman said: ‘We look forward to working with representatives from the member states, the Council and the Commission to ensure an orderly departure of the UK from the EU.’