When David Cameron delivered his resignation speech outside No 10 on Friday, he said he would leave the task of triggering article 50 of the Lisbon treaty – the untested procedure governing how an EU member state leaves the bloc – to his successor.

This has prompted much speculation – and a glimmer of hope for those who want Britain to remain in the European Union. Cameron, they argue, had repeatedly said during the campaign that article 50 would be triggered immediately if Vote Leave were to win the Brexit referendum.

By not doing so, the theory is, and by bequeathing the responsibility to whoever succeeds him, Cameron has handed the next prime minister a poisoned chalice. Given the dramatic reaction to Brexit – on world stock markets, on the foreign exchanges, in Scotland, across Europe – and with the enormity of the consequences of leaving the EU now plain, who will dare pull the trigger?

One consequence of this, as a below-the-line commenter argued on the Guardian website, is that Cameron has effectively snookered the Brexit camp: they may have won the referendum, but they cannot use the mandate they have been given because if they do so they will be seen to be knowingly condemning the UK to recession, breakup and years of pain.

This could mean, as lawyer and writer David Allen Green has suggested in a blogpost, that “the longer article 50 notification is put off, the greater the chance it will never be made ... As long as the notification is not sent, the UK remains part of the EU. And there is currently no reason or evidence to believe that, regardless of the referendum result, the notification will be sent at all.”

Is this feasible? Certainly, leading Brexit campaigners, including Boris Johnson and Matthew Elliott, who ran Vote Leave, have said very clearly they are in no hurry to push the button.

They argue it is far more sensible to hold informal talks with Brussels, and other member states, in order to arrive at the outline of a possible settlement before locking Britain into the strict two-year timeframe within which article 50 negotiations must be concluded (and if they are not, Britain risks having to leave the EU with no deal at all).

In Brussels and other EU capitals, the UK’s heel-dragging is already causing great frustration. European foreign ministers and EU leaders have lined up this weekend to impress on Britain the need for urgency. Brexit talks must begin “immediately”, they said, so as to avoid a sustained period of uncertainty and instability that, with Euroscepticism on the rise across the continent, could do great damage to the already weakened bloc.

But there seems to be no immediate legal means out of the stalemate. It is entirely up to the departing member state to trigger article 50, by issuing formal notification of intention to leave: no one, in Brussels, Berlin or Paris, can force it to. But equally, there is nothing in article 50 that obliges the EU to open talks – including the informal talks the Brexit leaders want – before formal notification has been made.

Martin Schulz, the president of the European parliament, expects Cameron to formally announce Britain’s EU exit on Tuesday evening. Photograph: Eric Vidal/Reuters

“There is no mechanism to compel a state to withdraw from the European Union,” said Kenneth Armstrong, professor of European law at Cambridge University. “Article 50 is there to allow withdrawal, but no other party has the right to invoke article 50, no other state or institution. While delay is highly undesirable politically, legally there is nothing that can compel a state to withdraw.”

The president of the European parliament, Martin Schulz, has said he expects Cameron to initiate the process on Tuesday evening, making the formal announcement that Britain intends to exit the EU at the summit dinner he is due to address before going home and leaving – for the first time – the other 27 member states to discuss Britain’s situation without him the following day.

The European council has confirmed that notification does not have to be in writing, but could be in the form of a formal statement to the summit – so Cameron had better be careful about what exactly he says.

But reports in German newspaper Süddeutsche Zeitung, among others, that an increasingly frustrated EU could, if push comes to shove, decide to consider the referendum result itself as “an official wish to leave” seem unreliable. “The notification of article 50 is a formal act and has to be done by the British government to the European council,” an EU official said.

“It has to be done in an unequivocal manner, with the explicit intent to trigger article 50. Negotiations to leave and on the future relationship can only begin after such a formal notification. If it is indeed the intention of the British government to leave the EU, it is therefore in its interest to notify as soon as possible.”

Even some EU diplomats are doubtful the article will ever be triggered, because the tight deadline for talks puts the leaver in such a weak position. “I personally believe they will never notify,” one diplomat said. “The moment you push the button you’re in a stupid negotiating position.”

Carl Bildt, the former Swedish prime minister, has said “de facto ejection” is a possibility unless Britain gets a move on, but it is unclear on what grounds that could happen. Article 7 of the Lisbon treaty allows the EU to suspend a member if it deems it to be in breach of basic principles of freedom, democracy, equality and rule of law. But that would be the nuclear option.

The situation could get quite nasty, quite quickly. Politically, the pressure on Cameron – and on his successor, whoever that may be – could be extreme. But legally, there does not appear to be any easy way out. If Britain so chooses, this could become a standoff that could drag on for years.

