For 100 years now, Irish republicans have refused to validate British sovereignty over the island of Ireland by sitting in the parliament of Westminster. As an abstentionist Sinn Féin MP, I can provide an Irish republican perspective on this issue.

To the British public, it may seem strange to stand for election to an institution and then refuse to participate in that institution. For British citizens with a progressive world view, and those with an anti-Brexit disposition, it might appear logical to take these seats, and for British MPs that is entirely logical – because the Westminster parliament is the democratic institution that makes decisions on behalf of the British people.

Gerry Adams: Brexit will be a disaster for the island of Ireland Read more

In recent weeks, in the light of Brexit negotiations and the Conservatives’ fragile majority propped up by the Democratic Unionist party, there have been calls from various quarters for Sinn Féin MPs to abandon the Irish republican principle of abstentionism and take part in the British parliament. A debate has opened up around this principle, particularly for a British audience which may not be aware of its political significance in Ireland.

Westminster does not now act – and never has acted – other than in the interests of Britain. As our difficult and troubled history tells us, the interests of the Irish people have rarely been the concern of the British government or parliament. In fact, these institutions have often acted against the interests of the Irish people – not just in the past, but as we are seeing now, through the efforts to drag us out of Europe against the democratically expressed wishes of the people in the north of Ireland.

The crucial point here is that we are not British MPs. We are Irish MPs and we believe the interests of the Irish people can only be served by democratic institutions on the island of Ireland. Sinn Féin goes to the electorate seeking a mandate for that position. We are elected as MPs by people who vote for Sinn Féin not to take seats at Westminster.

As MPs, therefore, we take no part in the Westminster parliament but in every other way we provide active representation for our constituents. We engage with British political parties, civic society and the Irish diaspora in Britain. We challenge the British government directly in our meetings with them. We lobby on constituents’ issues, and on all the political matters that affect the Irish people. We do all of this without drawing a salary from Westminster, or by taking our seats in the British parliament.

Quick guide Why is the Irish border a stumbling block for Brexit? Show Hide Counties and customs Inside the EU, both Ireland and Northern Ireland are part of the single market and customs union so share the same regulations and standards, allowing a soft or invisible border between the two.

Britain’s exit from the EU – taking Northern Ireland with it – risks a return to a hard or policed border. The only way to avoid this post-Brexit is for regulations on both sides to remain more or less the same in key areas including food, animal welfare, medicines and product safety. The 'backstop' in Theresa May's Withdrawal Agreement was intended to address this - stating that if no future trade agreement could be reached between the EU and the UK, then rules and regulations would stay as they are. This has been rejected by Brexit supporters as a 'trap' to keep the UK in the EU's customs union, which would prevent the UK striking its own independent trade deals. There are an estimated 72m road vehicle crossings a year between Northern Ireland and the Republic of Ireland, and about 14% of those crossings are consignments of goods, some of which may cross the border several times before they reach a consumer. Brexit supporters say this can be managed by doing checks on goods away from the border, but critics say it will be difficult to police this without any physical infrastructure like border posts or cameras, which could raise tensions in the divided communities of Ireland.

Interactive: A typical hour in the life of the Irish border Photograph: Design Pics Inc/Design Pics RF

Fundamentally, we believe that Britain and its political institutions should have no part in governing the people of Ireland. Why then, as Irish citizens, would we want to make decisions on behalf of the people of Britain?

The nature of the political and economic implications of British rule in Ireland has changed during this century, but the desire of Irish people to determine our own fortunes has not wilted.

The view of Westminster from Belfast is profoundly different to the view from Brighton or Bradford. Many Irish citizens in the north of Ireland view Westminster as a parliament that facilitated and supported 50 years of anti-Irish apartheid and supremacist sectarian rule in their towns and villages. They see a parliament that excused and endorsed the murder of Irish citizens by the British state during a period of conflict.

They see Westminster as the parliament that has denied them basic economic and political sovereignty, and decimated public services and social protections for the most vulnerable citizens.

Westminster is not their parliament, and never will be. That was demonstrated most cynically when, in 1981, the people of Fermanagh and South Tyrone elected the hunger striker Bobby Sands as their MP. Rather than recognise him as a political prisoner (how much more political can you get?), the Westminster parliament voted to stop this happening again. The lesson for the electorate of Fermanagh and South Tyrone, and the Irish people more widely, was clear: if we don’t like who you elect, we will change the rules to prevent you doing this.

The Irish people now see a parliament that runs roughshod over the integrity of their democratically expressed decision by enforcing Brexit upon them, threatening disruption to their border communities, and to their most basic rights and livelihoods.

The people of Ireland will not find a solution to Brexit in the parliament that is imposing it. On Brexit, Irish people in the north look to Sinn Féin, to the Irish government, the Irish parliament and to Europe to defend their interests.

Westminster cannot provide the solutions when Westminster is the problem. Its role in Ireland has never been positive. Numerically, culturally and politically, the people of Ireland are inconsequential to Britain’s ambitions.

Westminster has always turned its back on the people of Ireland, so the people have turned their backs resolutely on the British parliament.

This year republicans and progressives in Ireland celebrate the election of the first female MP to the British parliament 100 years ago. Her name was Constance Markievicz. She never sat in the Westminster parliament. She was an Irish republican, a feminist, a socialist, and a member of Sinn Féin elected on an abstentionist mandate – rejecting Britain’s claim to sovereignty over Ireland.

One hundred years later I am proud to follow in the footsteps of radical pioneers such as Markievicz.

In 2017, I and other MPs were elected on a mandate to actively abstain from Westminster. We intend to honour that mandate.

• Paul Maskey is the Sinn Féin MP for Belfast West