Slowly but surely, people are realising that the Brexit dream which they voted for is turning into a nightmare. The political and economic turmoil of the last four weeks (yes, it was fewer than four weeks ago) all had a single trigger; Britain’s vote to leave the EU.

But aside from the short-term mayhem which we are currently caught up in (and distracted by), there is a much more pressing, longer term question. Is the Britain which Brexiters voted for actually possible?

Tentative negotiations with Germany, France and Brussels have all suggested one thing: if we want free market access with Europe, we will have to put up with free movement of people. And conversely, if we want to “take back control” of our borders, we have to wave goodbye to the common market.

Immigration was cited as the number one reason for voting to Leave. And yet, as Cameron, Boris and Gove (all of whom suddenly disappeared) knew perfectly well, stopping immigration won’t be possible without permanently damaging the British economy – in a way that matters a lot more than the recent market turmoil.

This means that the only options available to the new Prime Minister, Theresa May are to either block Brexit – which she has already ruled out, and would be politically impossible, or to go back to the electorate with a second referendum, offering voters another chance to vote on the exit package – with an option to remain in the EU.

And this time, voters will actually be able to judge whether their reasonable expectations from the Leave campaign – of market access, less cost and less immigration – are delivered by the EU exit package on offer. However, the offer is likely not to be what “it said on the can” but less market access for a higher cost with the same immigration. So if the second referendum is either to accept the deal or to stay in the EU, I have a hunch that people will come home to the EU. After all, over four million have already petitioned for a second referendum, and estimates suggest that over one million Leave voters regret their decision (only 625,000 are needed).

It was therefore a shrewd idea of Theresa May to put Boris Johnson, David Davis and Liam Fox in charge of the Brexit negotiations. She must know as a Leave campaigner that the Brexiteers won’t be able to fulfil the public expectations they’ve created and so it is they who should carry the can of false promises they sold.

No one can really believe that Boris Johnson will be taken seriously by EU negotiators. They also know that within the year UK voters will conclude that the only option of saving jobs and the economy is to stay in the EU and that cast-iron control of immigration is both unrealistic and counterproductive. The new Prime Minister will then, in the interests of democracy, offer a second referendum “so that the informed and settled will of the people can be affirmed in light of the facts”.

When EU negotiators realise that a second referendum is more a question of “when” than “if” they will soften their position to allow negotiation before Article 50 is triggered i.e. before the two-year count-down to leaving the EU formally begins. That’s why I’m urging Labour Party members to contact their MP to sign Early Day Motion 243 which supports my Bill for a second referendum on the EU exit package.

Some say “let the dust settle” or “I don’t want to appear as sour grapes” but Labour needs to show strong leadership and to boldly embrace the inevitable whilst standing by members’ steadfast belief that we should remain strong in the EU. We need to surf the wave before it crashes on the beach. If we’re serious about shaping the future, we need to be rallying behind a second referendum on the EU exit package. Alternatively we can let Theresa appear to save the day.

Geraint Davies is Labour MP for Swansea West.