During the EU referendum, Brexit campaigners offered numerous reassurances about the rights of EU citizens. These assurances haven’t aged well, in fact – and I say this is as someone who voted Leave – they now seem very naïve at best.

Political events and the instability in which they have transpired have worked against the liberals and pragmatists. Good intentions have hurtled into the hard reality of the government’s anti-immigration policies and crumbled.

During the Tory leadership campaign all candidates who had been for Leave said they wanted to grant EU citizens unconditional guarantees. This never came to pass as the ultimate victor, Theresa May, thought it better to use them as bargaining chips.

Then, last year, the Commons rejected a Lords amendment to the Brexit bill to give all EU citizens in the UK permanent residency. This was a huge missed opportunity to do the right thing and resolve an issue that instead looms ominously over the whole Brexit process. Ever since, the anxiety of EU citizens has been increasing.

When the EU questioned the reliability of British guarantees and insisted on a role for the European Court of Justice in upholding the rights of EU citizens, many Brexiteers were outraged and insisted that the laws of this land were guarantee enough. The Windrush scandal has embarrassed this country, vindicated the EU and should raise alarm bells.

As we speak, the government is actively in the process of building a system that is risking another major crisis in a few years’ time. The future of a whole new generation of migrants is being put in jeopardy.

The Windrush crisis came about because the inflexibly enforced ‘hostile environment’ persecuted a group of migrants that had been granted citizenship rights, had no previous need for paperwork and documented evidence of their rights and didn’t consider themselves ‘migrants’. It isn’t hard to see the major problem brewing here, with all the same key factors set to produce a future EU migrant crisis.

Instead of certifying their existing rights, the government is designing a new system to give EU citizens who live in the UK ‘settled status’. This will go some way to managing the problem, but with compulsory application comes the risk of error and people falling through the cracks. If the government can’t manage the immigration status of a relatively small number of longstanding British citizens, how they will they cope with 3.7 million EU citizens? The Home Office has an error rate of 10%, a margin of error which could imperil 370,000 people.

There are several high-risk groups that might fall foul of this process and end up being targeted. For example, children whose parents don’t apply and children who were born in the UK and whose parents mistakenly believe they are automatically UK citizens, will have serious problems with a callous Home Office in the future.

There are 146,000 non-Irish long-term residents who arrived at least thirty years ago who are at risk of a Windrush style debacle. Under the hostile environment, someone in their 40s who arrived from Europe as a child in the 70s, who has lived and worked here all their life, think of themselves as British and goes about their daily life without a concern about their rights, could well end up receiving a Home Office letter.

Just like the Jamaican child who grew up here and never realised the government didn’t consider him really British, people who came from the continent could be victimised in the future. With their immigration status brought into question they could be evicted, lose their job, be denied healthcare and end up with enforcement officers on their doorstep.

Other vulnerable groups include pensioners who have been here for decades and the elderly with health issues and victims of abuse. All in all, the Migration Observatory predicts that hundred of thousands of people could be at risk.

The real point is that people have complicated lives and amongst the 3.7 million EU citizens there will be a great many complicated cases. The Home Office has shown us unequivocally that it is not able or willing to manage such complications. Instead, the whole system is designed to make life unbearable for those that fall through the cracks.

We can’t afford to be complacent and let this fade into the background. After the transition phase has ended, and the ‘grace period’ allowed for EU migrants to deal with their status is over, those left with an uncertain status will fall victim to the hostile environment policy.

I can see it now, years after leaving the EU Britain has repaired its reputation which was damaged by the negative perceptions of Brexit. Both Europe and Britain have moved on and its new partnership is working well. Britain is looking to the future. Then come the horror stories.

The Polish nurse who has lost her job and been threatened with deportation. The Spanish care worker denied healthcare. The Portuguese cleaner sent to a detention centre. The Dutch engineer in the media telling the harrowing story of when they got that knock at the door. Thousands of people who are fully integrated into our society and consider this their home, suddenly being targeted, victimised and given a status of ‘otherness’.

Without fundamental reform or policy, we could be heading for a social disaster that will seriously tarnish the reputation of this country. The government should review its immigration policies and end the ‘hostile environment’ approach.

To avoid a crisis, EU citizens who came to this country under free movement rules should have their existing rights legally guaranteed. In addition, long term residents should be offered the option of full citizenship rights. The Conservatives should leap at this chance to do the moral thing and detoxify their image. Brexiteers should be especially enthusiastic to show that Brexit isn’t a xenophobic spasm.

For the most part we have invited into our country some of the most industrious, entrepreneurial and well-educated people that Europe has to offer. Brexit, initially, will be about conserving the assets we have; this includes people.