A documentary following the road to the marriage equality referendum is being shown on Netflix.

'The 34th' tells the story of people who formed marriage equality in Ireland, and developed it into an effective grassroots force.

They had one clear goal in mind - the extension of civil marriage to same-sex couples.

Through revealing interviews and archive material, former board members and staff outline the strategising, fierce battles, sheer hard graft and personal cost of running such an all-consuming campaign.

It covers topics from the Katherine Zappone and Ann Louise Gilligan legal case, to a 'Yes' vote on May 22nd 2015.

Katherine Zappone with her wife, the late Ann Louise Gilligan, during the counting of votes in the 2016 general election | Image: RollingNews.ie

As Minister Zappone explains: "Ann Louise and I had the opportunity to marry in Vancouver - every other couple that would go off to Canada to get married would come back to Ireland and get recognised by the Registrar General or the Revenue Commissioner and they'd just sign the papers and everything would be fine.

"But when we looked for our recognition, the State said no."

"So we wrote the Registrar General to say 'we'd just like to register our marriage' and we wrote to the Revenue Commissioner just to change our tax status.

"And that's when we received, especially from the Revenue Commissioner, back that incredible letter that said 'Dear Ladies, we can't give you a change of tax status because the definition of marriage here in Ireland was between a man and a woman'.

"And we said: That's the letter that we need to go to court".

The documentary spans a decade, culminating in the 34th amendment to the Constitution, allowing same-sex marriage.

The film originally opened at the 25th GAZE International LGBT Film Festival, where it was highlighted by the panel as the film that best embodied the spirit of the festival.

It received the 'Spirit of Gaze Award' along with the 'Audience Award'.