Westminster government has said it will honour both results despite ministerial doubts

MPs have voted resoundingly to extend same-sex marriage and access to abortion to Northern Ireland, bringing the region into line with the rest of the UK on the two significant social issues.

The two historic votes, arriving within little more than a quarter of an hour of each other, were greeted ecstatically by equalities campaigners. With ministers promising to respect the results, they could have vital repercussions for people in Northern Ireland.

Both were the culmination of long campaigns by backbench Labour MPs, who said the government’s argument that the changes could only be made by the devolved Northern Irish government was defunct, given it has been suspended amid political deadlock since the start of 2017.

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The changes came via amendments to an otherwise technical government bill connected to budgets and elections for the devolved assembly. In the first amendment, tabled by the Labour MP Conor McGinn, a longstanding campaigner for equal marriage in Northern Ireland, the Commons voted 383 to 73 to extend it to the region.

In a vote soon afterwards, MPs approved an amendment by another Labour MP, Stella Creasy, to extend abortion rights to Northern Ireland, the only part of the UK where it remains illegal. The vote was passed by 332 to 99.

Both were free votes as they were viewed as matters of conscience. While the Northern Ireland minister, John Penrose, who spoke for the government, warned MPs that both potential changes would be fraught with complications, he voted in favour of both amendments.

McGinn’s amendment would theoretically lead to an automatic change in the law within three months if the devolved government remained stalled, although Penrose warned it might take longer owing to legal practicalities. If and when the region’s executive is revived, it can then approve or repeal the measure.

McGinn credited the work of Love Equality, a Northern Irish campaign for equal marriage, and said LGBT people in the region had been “let down so many times before”.

The MP, who comes from Northern Ireland but represents St Helens North in the Commons, said he hoped the devolved executive and assembly would be working again within the three-month deadline and would make the change.

“But if Stormont still isn’t functioning by then, the LGBT community in Northern Ireland will know that Westminster will act to ensure equality and respect for all citizens, and finally give them the right to marry the person they love,” he said.

Creasy’s amendment argued that abortion laws in Northern Ireland, where women seeking a termination can face life imprisonment, were contrary to international human rights norms.

“How much longer are the women of Northern Ireland expected to wait?” she told MPs. “How much more are they expected to suffer before we speak up – the best of what this place does – as human rights defenders, not human rights deniers?”

After the vote, Creasy tweeted: “Thank you to everyone who today stood up for equality in Northern Ireland – whether for same-sex marriage or abortion, today we have said everyone in the UK deserves to be treated as an equal. There’s a road to go yet but today a big step forward.”

Both votes were also hailed by rights groups. Amnesty International’s Northern Ireland director, Patrick Corrigan, said the equal marriage decision was “a day for the history books”. Marie Stopes UK, which campaigns on access to abortion, said the Creasy amendment marked “a historic day for women’s rights”.

Amid a flurry of amendments tabled, another one which passed has a very different impact: it makes it potentially harder for a future government to prorogue parliament so as to ensure a no-deal Brexit.

The amendment, by the remain-minded Tory MP Dominic Grieve, would require a minister to report to the Commons every two weeks until December on the progress of talks on restoring the Northern Ireland assembly. It passed by a single vote: 294 to 293.

The idea is that the legal requirement for these regular reports would stop a new prime minister suspending parliament to prevent MPs blocking no deal, something Boris Johnson has refused to rule out.

Before the equal marriage and abortion votes, Penrose said the government would honour the results, despite ministerial doubts. “Should this pass it will go into law,” he said. “It will become part of primary legislation. And so ministers will be bound by it and the government will proceed.”

In Northern Ireland, the votes were welcomed by the centrist Alliance party and the moderate nationalist SDLP, but Unionist leaders reacted angrily.

Nigel Dodds, the Democratic Unionist party (DUP) leader in Westminster, warned before the votes that they would drive “a coach and horses through the principle of devolution”.

Jim Allister, the leader of the small Traditional Unionist Voice party, urged the DUP to use the leverage of its confidence-and-supply agreement with the Conservative government to “thwart” the MPs’ decisions.

The votes could also affect efforts to revive the executive and assembly at Stormont. While Naomi Long, the Alliance leader, said they could unlock the talks, others speculated that Sinn Féin, which supports social liberalisation, now has an incentive to delay the restoration of devolution to let the amendments take effect.