250 people attended a vigil outside an anti-marriage equality conference in Tasmania last night as it was revealed the winning video message in the conference’s competition to define an ‘excellent marriage’ was from a gay man.

The Excellent Marriage conference was attended by around 350 organisers said today, with an address by former senator Guy Barnett that focused on children.

In his address to the audience, which included former tennis champion and equal marriage opponent Margaret Court, Mr Barnett, who opposed attempts to decriminalise homosexuality in the state in the early 1990s, said marriage equality would “neglect the interests of children”.

Mr Barnett claimed equal marriage would overturn the child’s “right to a relationship with their natural brothers, sisters, cousins and broader family members”.

Allowing gay couples to marry and adopt children would perpetuate the “tragedy” of anonymous sperm donation, he argued, cutting children off from their biological parents.

Although registered gay partnerships were “appropriate”, Mr Barnett said: “The marriage union is publicly recognised and treated as special and unique distinguished from other types of relationships because of its unique capacity to generate children and meet children’s needs. Of course not all married couples have children and many married couples adopt but marriage is the foundation stone for procreation.”

The vigil attendees held placards outside with slogans including ‘Equally excellent’ and ‘same sex, same rights, marriage equality now’.

Rodney Croome of the Tasmanian Gay and Lesbian Rights Group said: “It was wonderful to see so many people from such a diverse range of backgrounds attending the vigil.

“As well as LGBTI people and our family members there were representatives from the union movement, Young Labor and Amnesty International, and many young heterosexual families with children, and older heterosexual couples.”

“Those attending the ‘Excellent Marriage’ rally were under no illusion about how widely and strongly the pro-equality cause is supported.”

Vigil organisers say they were offered hot chocolates by some young Christians but “politely declined”.

The “Excellent Marriage” conference had also asked people to submit a video explaining what they thought constituted an excellent marriage. A $500 prize was to be awarded to the most popular clip.

Rowan Carmichael entered the competition to show his support for marriage and, in the video below, speaks briefly about the importance of the union.

Mr Carmichael was later revealed to be gay and his entry was temporarily removed from the competition.

He said: “I entered the competition because I wanted to show that a gay man can want an excellent marriage just as much as anyone else, and that we all have more in common than apart.”

“When the organisers of the competition felt I was hiding something from them they removed my entry, but friends, family and some supportive clergy vouched that what I said in the clip is what I genuinely believe and it was allowed to stay in the competition.

“In the end I won by about forty votes.”

Mr Carmichael’s $500 was reportedly not presented last night, but was congratulated by equal marriage opponent Rev Campbell Markham at the conference.