It may be several months before the UK can make its departure from the EU official, an expert has warned.
The UK's vote to leave the European Union is unprecedented, leaving those in charge scratching their heads over what happens next.
What's clear is the UK will have to trigger Article 50, the formal mechanism for leaving the EU. But Pawel Swidlicki, a policy analyst at think tank Open Europe, told City A.M. it was likely to be several months before the mechanism can be triggered.
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"The UK needs to formulate a new plan for how it approaches negotiation with the EU. David Cameron did talk about triggering [article 50] immediately. We think that's unlikely. Ultimately, David Cameron has a responsibility towards the country, and to trigger it immediately would not be the responsible thing to do."
He added there are "three ways" the UK can negotiate its exit from the EU.
"Stay and negotiate standalone access to the EU area - the Norway model - the Canada model [which gives it almost comprehensive free trade with the EU], or reverting to WTO rules.
"The latter would be the most economically disruptive, but would also allow the UK to have the most freedom."
Research published by Cambridge law professor Kenneth Armstrong earlier this week suggested Article 50 is the only way the UK can leave the Union.
Under the rules, the UK would remain a member of the EU for two years while negotiations take place. Although that period can be extended, any EU state could veto an extension, forcing the UK "into a take-it-or-leave-it dilemma," wrote Armstrong.