In a column in today’s Irish Independent Brennan outlines the reasons he would be voting No on May 22.

“I am voting "No" because I don't want our Constitution to deny that it is a good thing for a child to have a mother and a father,” Brennan said.

“The Universal Declaration on Human Rights proclaims that everybody is equal in dignity and it holds that marriage is a male-female union. I don't think the Declaration of Human Rights is homophobic. I'm voting 'No'.”

Brennan also said: “I know I'm not homophobic; my gay friends and family can attest to that.”

Brennan can point to his acceptance speech in Croke Park in March 2014 as proof of that.

He captained St Vincent’s to the Club Football All-Ireland and in his acceptance speech thanked both the girlfriends and boyfriends of the team for their support - a move widely praised by equality groups at the time.

Conor Cusack took the opposite view on the issue while speaking to Anton Savage on Today FM, even though he said he did not think Brennan was homophobic.

“Ger made, what I would say, was a very powerful statement in Croke Park last year when he accepted the cup with his club St. Vincent’s when he thanked the players’ boyfriends and girlfriends,” Cusack explained.

“It was a really pivotal moment."

But he insisted that Brennan was mistaken in his views on what it meant for children.

“We keep hearing about kids, but what about those kids that happen to be lesbian, gay, bi-sexual or transgender?” Cusack asked.

“Being an effective parent isn’t about your biology or your genitals, it’s about the quality of love that you bring to a family.”

Cusack, who has spoken before about his own sexuality, said a Yes vote would be a powerful message of acceptance to the LGBT community in Ireland.

“We are fighting for equal rights,” he said. “The weapons we are using are the truth of our stories and the authenticity of our love. I hope that’s the thing that will get through to people.”