Mark Field is MP for the Cities of London and Westminster, and a Vice-Chairman of the Conservative Party.

A huge paradox lies at the heart of the Leave campaign. For years, arch-Eurosceptics have been telling us that the EU acts as a conspiracy against our national interests and that no UK government is capable of negotiating a deal with fellow Europeans that works for us. Nevertheless the moment we vote to leave, the EU will – or so we are told – roll out the red carpet to ensure that we are afforded the very best terms on future trade and commerce arrangements.

To question this somewhat implausible theory will doubtless be branded as the latest incarnation of Project Fear. In truth it is Project Fact.

Those peddling the disingenuous line that the EU will simply roll over and make life easy for a nation that unilaterally departs the organisation are guilty of wishful thinking to the point of wanton irresponsibility. I guess it is plausible that our erstwhile EU allies might choose pragmatism over antagonism, but it would surely be mighty unwise to rely on this.

In truth, a UK exit would raise existential issues for the European Union, and its remaining members, especially Germany, would simply not allow others to be given any encouragement to follow suit. Making life difficult for the UK in the event of a unilateral decision to leave would be a near certainty lest other nations (Denmark, Sweden and the Netherlands immediately come to mind) were tempted to go down the same path. Admittedly this is what Brexiteers want, but we should not assume that the EU will ease their path!

Contrary to the urban myth peddled by the Leave campaign, many of whose supporters have always sought exit from the EU regardless of any amount of reform or concessions, David Cameron’s renegotiation achieved a more extensive package of safeguards than has been managed by any European leader since De Gaulle.

I accept that for many Eurosceptics even the establishment of Special Status for the UK reinforcing our exclusion from the Eurozone and Schengen does not go anything like far enough. However, we should also recognise that Angela Merkel has used up significant goodwill in persuading other EU nations to allow us this bespoke deal. If Brexit now results, Europe’s leading government head will simply wash her hands of the ‘British question’. Terms for renegotiation of our exit will become the responsibility of the European Commission, led by Jean-Claude Juncker, an individual not renowned for his pro-British sympathies. This would potentially represent a calamity for our chances of extracting ourselves from the array of European treaties smoothly and with a satisfactory outcome acceptable to UK businesses and voters.

Forget about getting a deal within two years as envisaged in the Lisbon Treaty. It will take longer, with all the uncertainty so damaging to UK business interests. Forget too about getting a ‘Norwegian or Swiss-type deal’ – the EFTA/EEA arrangements were drawn up a different time in a different world. If the UK unilaterally leaves at this critical juncture it will not be for us to dictate the terms of our exit treaty. Goodwill, cooperation and even concessions will be thin on the ground as we extricate ourselves. Remember, too, that as former WTO head, Pascal Lamy, put it, ‘trade negotiations are not about love, they are about numbers, they are about clout and bargaining capacity. Standing alone, the UK loses the bargaining capacity…so outside in the cold this means more imports, but less exports’.

Perhaps we also need to be clear that Angela Merkel will have a very different set of priorities after 23 June – after all, she has a domestic election to fight and win in September 2017. As a result the German Chancellor’s energies will be expended on tackling Germany’s own domestic economic and migration challenges. To be frank, without Merkel’s support and close attention the UK should not bank upon getting a merely satisfactory treaty to depart yet alone the all-singing, all-dancing deal that Leave confidently suggest is there for the taking.

Nor should we expect support from other quarters. Countries in danger of breaking apart – Spain, Italy and Belgium in particular – will be allergic to the UK’s stance, not least if it has resulted in another push for Scottish independence.  As for Central European nations, often our staunchest allies in the EU, they will be furious at our desertion of a united front against a resurgent Russia whose leader is the only leading global head of state encouraging Brexit. Indeed already in Poland and Hungary we see some unravelling in the Western liberal order – Brexit might ignite further nationalistic, populist and isolationist forces across this region. Ireland will be unhappy that the status of the North again becomes a political hot potato. When the Article 50 talks begin on our exit deal, we would have few, if any, allies.

Leavers and even many on the Remain side may lament the fact that within the EU the UK’s room for manoeuvre is necessarily constricted in certain areas but we need to accept the world as it is, not with the starry-eyed vision often painted by those promoting Leave. Rather than wishing these practical difficulties away, the UK needs to take a hard-nosed, practical view about the problematic path that will lie ahead if at this critical time in the global economy we decide to leave the EU. I should contend as a consequence that the uncertainty and risks of Brexit are simply far too great.