Elmar Brok. Photograph: Francois Lenoir/Reuters
There were early warnings of difficulties ahead. The German MEP Elmar Brok, who chairs the European parliaments committee on foreign affairs, told the Guardian the parliament would call on Juncker to strip the British commissioner, Jonathan Hill, of the financial services brief with immediate effect and turn him into a commissioner without portfolio.
He said: They will have to negotiate from the position of a third country, not as a member state. If Britain wants to have a similar status to Switzerland and Norway, then it will also have to pay into EU structural funds like those countries do. The British public will find out what that means.
Jean-Claude Piris, a former head of the EU council legal service, said claims that Britain would get unfettered access to the single market, without free movement of people, were the equivalent of believing in Father Christmas. He said the British cannot get as good a deal as they have now, it is impossible.
Some Brussels insiders fear France and Germany may soften their approach after the vote. Others think countries, especially France, will push for a harsh settlement to hammer home the price of leaving.
One likely outcome of negotiations is that banks and financial firms in the City of London will be stripped of their lucrative EU passports that allow them to sell services to the rest of the EU.
However, on paper, nothing changes immediately. The UK remains an EU member until it has finalised the terms of its divorce and is obliged to follow all EU rules.
In theory, the UK retains the decision-making privileges of membership; in reality, power will rapidly drain away and British diplomats can expect to be marginalised in the councils of Brussels.
The UK will keep its veto in some areas, such as tax and foreign policy, but diplomats say Britains voice on other EU decisions, for example economy and business, will count for little.