It followed a debate in parliament initiated by Labour MP Stella Creasy to repeal parts of the 1861 Offences Against the Persons Act.
Because the 1967 Abortion Act was never extended to Northern Ireland, the 1861 Act is the legislation that governs abortion there.
Abortions are only permitted when a woman’s health is deemed to be at “serious risk”.
Shadow Labour home secretary Diane Abbott told the demonstration “when it comes to equal rights, women’s bodies are ground zero.”
“It’s completely wrong that women in Northern Ireland are the only part of the British Isles that don’t have these rights.”
During the debate Northern Ireland secretary Karen Bradley reaffirmed Tory prime minister Theresa May’s position of inaction.
May is scared to intervene because the Democratic Unionist Party—which is propping up her government—is anti-choice.
Bradley said, “It would not be appropriate for Westminster to seek to impose its will.
“Personally I want to see reform in Northern Ireland—but it is a matter for the people of Northern Ireland,” she said.
But activists are demanding extension of the 1967 Act now.
Danielle Roberts, from the Northern Irish Alliance for Choice campaign said, “We don’t need a referendum and we don’t want one.
“We know the public support has changed and it’s the politicians who are out of step and they’re not doing their jobs anyway as [the Northern Ireland assembly] Stormont has been down for a year and a half.”
Pointing at parliament, Danielle said, “That house has the power to legislate”.
In her speech on Monday arguing for a debate on the legislation, Creasy said “The impact of the Irish referendum has been felt around the world.
“2.1 million people voted, of which 1.4 million voted to repeal article 8, which prevents abortion.
“In doing so, they have thrown a spotlight on the situation in Northern Ireland, where a million women are affected.”
Sonia Adesala from Doctors for Choice told Socialist Worker that the fight must be for "decriminalisation across the UK and to design regulation that puts women's health and wellbeing at the heart of everything.”
Many were keen to point to the opportunities last month’s historic vote in Ireland presented.
A protester from Northern Ireland told Socialist Worker tTuesday's demonstration was “incredibly moving”.
And, she said “the referendum has opened up a conversation, because we all knew women who had travelled (for abortions) but never talked about it.”
The pressure must be kept on May and the Tories to extend the 1967 Act to Northern Ireland as it should have done 51 years ago.