His viewpoint on Brexit goes beyond party political issues, to the human misery and damage it is causing.

Alberto Costa’s views on Brexit are those of a worried family man. A quiet Scot, he stood up in the UK House of Commons and spoke, not about economics or national sovereignty, but about right and wrong.

Mr Costa tabled an amendment to a UK government motion; he did so to protect his parents and millions like them. It was debated on February 27 and the vote made history.

In his Commons speech, he said: “My amendment does not deal in goods or services, backstops or borders, but people — living and breathing, skin and bone. The rights and freedoms of over one million UK citizens in the EU, and over three million EU citizens in the UK, should never have been used as a bargaining chip during the negotiations for our withdrawal from the European Union. That such rights were placed on the table in the first place was wrong.”

Three million people from the EU, permanently settled by right in the UK for years or decades, are suddenly having to apply to stay in their homes.

Even the UK Home Office’s own target is a 95% success rate for their “settled status” scheme, which means that it expects 150,000 EU citizens to be unable to prove their right to stay in the UK. A right they never before had to prove, because, well, it was a right.

Similarly, 1m people from the UK have built their lives on the EU project and the freedom of movement it offers. They have moved to work in other countries, fallen in love, settled down, made new homes.

My family is among them. I’m a Scot, like Mr Costa, and came from Scotland to Ireland via England, Germany, and Romania. My wife and most of my family are Romanian.

UK citizens are secure within Ireland, because of old and new bilateral agreements. But others all over the EU, permanently settled by right according to EU law, are now having to deal with a multiplicity of registration schemes to stay in their homes. Their EU rights to social welfare and healthcare will be lost.

People who work in more than one EU country will not be able to after Brexit. To add insult to injury, new immigration restrictions on EU citizens mean that many mixed UK/EU families will be unable to go back to the UK, even if it was previously their home.

Returning to the EU partner’s home country may also be difficult or impossible. Returning to Europe from a work contract elsewhere in the world may be out of the question.

So the imaginary safety net of “if it doesn’t work out, we can always go home” doesn’t exist for some of us, and, for many, moving to be close to the grandchildren suddenly becomes near impossible. My own family is affected.

Since the 2016 EU referendum on Brexit, citizens’ groups have been campaigning to protect our rights. The 3 Million works for EU citizens in the UK, and British in Europe works for UK citizens elsewhere in the EU.

Both the EU and the UK have maintained that citizens’ rights are their top priority; but in the withdrawal negotiations themselves, we have become bargaining chips, and our rights have been quietly, steadily, and covertly chipped away.

The EU set out to protect all our existing rights, but the UK government’s aim was to end free movement for EU citizens. As it eroded their rights in the UK, corresponding restrictions were placed on UK citizens in the EU.

Although the final withdrawal agreement is far more restrictive than the EU first intended, it is still good enough for most of us, most of the time — and, crucially, it would be an international treaty, so our rights would not depend on the vagaries of changeable national laws. We don’t want to lose even that, in a no-deal scenario.

This is why the Costa Amendment is so fundamental, and so welcome, because it would protect Part 2 of the withdrawal agreement, the part that deals with citizens’ rights.

Without the Costa Amendment, a no-deal Brexit (which is looking increasingly likely) would destroy Part 2, along with all the rest, because of the principle that “nothing is agreed until everything is agreed”.

In fact, everything has been agreed, between governments, but the UK parliament continually refuses to ratify the withdrawal agreement. Conservative MPs in the anti-EU European Research Group (ERG), along with the Democratic Unionist Party (DUP), are unhappy about the ‘backstop’.

This is the part of the agreement that protects against a hard border in Ireland. Vote after vote reinforces the message that the House of Commons is divided on the issue.

Yet, in contrast to its habitual disunity on Brexit, the House of Commons did something exceptional when it adopted the Costa Amendment. When the vote came, there was a chorus of “ayes” in favour; the speaker asked for the “no” votes, but not a word was heard.

Every MP present had supported it, across the Brexit spectrum, from the pro-EU SNP, Liberal Democrats, Plaid Cymru and Green parties, all the way to the ERG and the DUP. Alberto Costa had done the seemingly impossible — he had united the Commons in a Brexit vote.

So, are we safe now? Can we all breathe a sigh of relief, knowing our rights are protected? Not quite. The Costa Amendment, valuable though it is, is an instruction to the UK government to seek agreement with the EU. The EU still needs to agree it, if we are to be safeguarded.

Press reports in the UK about the Costa Amendment often say things like “Brussels refuses to negotiate a mini-deal on citizens’ rights”. This shorthand is misleading.

The Costa Amendment is not asking for a “mini-deal” on citizens’ rights, separate from the withdrawal agreement. Citizens’ rights are already in the withdrawal agreement, and it would be absurd to negotiate them again.

The Costa Amendment says that if we are facing the cliff-edge of a no-deal Brexit, the citizens’ rights part of the withdrawal agreement would become the deal.

There’s a name for something that you hope you won’t need to use, but you still have, in case the worst happens and nothing can be agreed in time. That name is familiar to us here in Ireland. It’s a backstop. The Costa Amendment proposes a backstop for human rights.

So, what has to be done to get Brussels to agree to it? Firstly, we have to be clear about what Brussels is shorthand for. The EU’s decisions are made by the Council, which consists of the heads of government of its 28 (soon 27) member states, and by its directly elected parliament; the decisions are implemented by the Commission, which is the EU’s civil service.

‘Brussels refuses to negotiate this’ means ‘The Commission doesn’t have a mandate to negotiate this.’

This is true and not surprising. They are, after all, civil servants, allowed to do only what the Council has instructed them to do: to negotiate one single withdrawal agreement, which they have done.

To get Brussels to agree to protect citizens’ rights in a no-deal Brexit, as the Costa backstop proposes, the Council has to give a new mandate to the Commission to negotiate it with the UK.

Taoiseach Leo Vardakar is one of the 27 members of the Council, so he and his 26 counterparts, heads of government from around the EU, have our fate in their hands.

The latest statement from the Commission is that protecting Part 2 in this way “would imply that the negotiations have failed”.

But a backstop doesn’t imply failure: it’s just a safeguard, in case negotiations do fail. The backstop we already have doesn’t imply that future negotiations on the border in Ireland are going to fail; the clear intention is that they wil succeed, but the backstop is there, just in case.

The same applies to the Costa backstop. Their common feature is that they both protect human rights: one protects the rights of people on the border and in the North; the other, people all over the EU and UK.

Until Wednesday February 27, Alberto Costa was a parliamentary private secretary, the first rung on the ministerial ladder. It is not quite true to say he was “sacked”, as some reports have stated.

Just before entering the Commons chamber, the UK prime minister, Theresa May, spoke to Mr Costa, and reminded him of what was expected of him. As he explained in parliament: “There is a convention that a parliamentary private secretary is expected to resign if they table an amendment [to government policy], which is all I would say on the matter.”

Even at that moment, he was too honourable to utter a word of criticism.

Mr Costa thanked fellow MPs with these words: “We can all take pride in informing our constituents and fellow British citizens in the EU that we put citizens’ rights at the very front”. Then, he thanked The 3 Million and British in Europe.

Finally, he closed his speech with a reminder, as valid in the EU Council as it is in Westminster: “Citizens’ rights is not about party politics. It is about people”.

People like me and my family, like friends in the UK and around Europe, thousands who are suffering anxiety and illness, because our rights are under threat.

The more than 4m innocent victims of this Brexit tragedy.

The EU Council meets on March 21 and 22, only a few days before Brexit. Previously, both EU Council and Parliament have consistently been far more generous about citizens’ rights than the UK government. We hope they have not forgotten that generosity, in their frustration with the UK’s capricious indecision.

Over 4m of us are hoping or praying that they will remember Mr Costa’s closing words. This is not about politics; it is about people.

Gordon Reid is a member of The 3 Million and British in Europe, and Green Party local candidate for Bandon-Kinsale