Downing Street has quashed a suggestion by Boris Johnson that a second referendum could be held on Britain’s relationship with the EU even if the UK votes to leave in the poll on 23 June.

As David Cameron prepared to outline his plans to change Britain’s relationship with the EU, No 10 said the prime minister would invoke article 50 of the Lisbon treaty – the mechanism for leaving the EU – in the event of a vote to leave. This would trigger two years of negotiations after which the UK would be presented with a take-it-or-leave-it package by the EU.

Downing Street dismissed the idea of a second referendum after the London mayor indicated that a vote to leave the EU could create the conditions to renegotiate the terms of Britain’s EU membership.

In his weekly Daily Telegraph column, Johnson wrote: “There is only one way to get the change we need, and that is to vote to go, because all EU history shows that they only really listen to a population when it says no... It is time to seek a new relationship, in which we manage to extricate ourselves from most of the supranational elements.”

The suggestion by the London mayor shows the influence of Dominic Cummings, the Vote Leave campaign director and former special adviser to Michael Gove, who has suggested that Cameron should use a leave vote to demand better terms from the EU.

Cummings believes the prime minister should hold his nerve if he loses the referendum and refrain from invoking article 50, which would trigger two years of exit negotiations. This would be designed to put pressure on EU leaders to negotiate a new “grand bargain” between Britain and the EU.

Vote Leave is not officially committed to the idea of a second referendum because such a move would probably disqualify it from winning designation from the Electoral Commission as the official leave campaign. The commission can only designate lead campaigns on either side of the referendum that are fully committed to taking the UK out of the EU on the leave side or keeping the UK in on the remain side. But Cummings is still committed to the idea of a second referendum as a way of reaching out to undecided voters who may be alarmed by the idea of a definitive break with the EU.

Cameron’s position was backed by senior officials in Brussels who emphasised that “no means no” in the referendum in June and that a rejection of EU membership by the British would trigger further negotiations, but only on the terms of the divorce.

The conclusions of the Brussels summit on Friday stated that “it is understood that, should the result of the referendum in the United Kingdom be for it to leave the European Union, the set of arrangements will cease to exist”.

This point was pushed by the Belgian prime minister, Charles Michel, but he enjoyed support from other national leaders.

It is understood that Donald Tusk, the president of the European Council who brokered the UK settlement terms and chaired the summit, takes the view that there will be no second round of negotiations if Britain votes to leave the EU.

In previous referendums on EU matters, for example in Ireland and Denmark, No verdicts have been followed by further negotiations and then referendum re-runs.

But Tusk is understood to believe that a British No vote will have to be respected by the rest of the EU and taken as final.

“We should be clear,” said a senior EU official. “This agreement lapses. That’s the agreed position of all 28 [governments] and [European commission] President Juncker. I won’t speculate any further.”



The prime minister’s spokeswoman said Cameron would invoke article 50 though he would be unlikely to do this at the summer European council, which will open on 23 June, the day of the referendum. The summit will conclude at lunchtime on Friday 24 June, by which time the referendum result will be known. A vote to leave would immediately annul the agreement Cameron signed with EU leaders last Friday.

The spokeswoman said: “The process is set out very clearly in the treaties. A vote to leave is a vote to leave. The prime minister stood on a manifesto that made clear that this government would give the British people a choice whether to remain in the EU or to leave – a very simple, straightforward choice, remain or leave. If the British people vote to leave then the government will clearly respect the outcome of that; it will then launch the process to leave and that is set out clearly. It is a two-year, time-limited process.”

Once article 50 is invoked, the UK would lose its seat on the European council, which is made up of the EU’s 28 leaders. The remaining 27 leaders would appoint two member states to negotiate a UK exit over two years. This would then be voted on in the European council through the process of qualified majority voting where no country has a veto. It would then have to be approved by the European parliament.

The prime minister will promote his EU reform plan in a white paper that will be published on Monday. The government will also introduce the secondary legislation to allow the referendum to be held on 23 June and to allow the Electoral Commission to designate the lead campaigns.