A straight couple will be next to challenge the UK’s ban on gay marriage and straight civil partnerships.

Andrew O’Neill, a comedian, and Stephanie Munro, an administration manager, say that marriage is patriarchal and they do not want to be part of an institution which bars gays and lesbians.

They are one of the eight gay and straight couples challenging the twin bans through the Equal Love campaign.

The couple will go to Camden registry office in north London tomorrow to register a civil partnership. After they are rejected, they plan to take legal action through the courts.

Ms Munro, 27, said: “The institution of marriage has never appealed to me and it certainly doesn’t reflect my relationship with Andrew. We’re partners and we want to make an official, lifetime commitment to each other. But we don’t want to participate in a marriage system that has patriarchal foundations and rejects same-sex couples.

“The segregation of same-sex and different-sex relationships into predefined categories is discriminatory and entirely unacceptable to us.”

Mr O’Neill, 31, added: “As long as marriage is denied to same-sex couples, it remains a hangover from a patriarchal age. The handing over of the bride from one male to another is enshrined in the marriage ritual and, to a degree, in law. That’s one reason why marriage doesn’t seem right for us. A civil partnership has none of this historical baggage.

“While I reject the social pressure to get married, I see clear benefits in the legal status of civil partnership. I also strongly believe in equality of opportunity for same-sex couples.”

Peter Tatchell, who is leading the campaign, commented: “Denying heterosexual couples the right to have a civil partnership is discriminatory and insulting. We want to see it ended, so that straight couples like Andrew and Stephanie can have the option of a civil partnership. I salute their challenge to this unjust legislation.”

Ms Munro and Mr O’Neill will be the sixth couple to register for a ceremony they are not entitled to. It is hoped that the remaining two couples will attempt to register ceremonies before Christmas.

Once all eight couples have been rejected, they will begin legal action.

Their lawyer, Professor Robert Wintemute, said: “There is no longer any justification for excluding same-sex couples from civil marriage and different-sex couples from civil partnership.

“It’s like having separate drinking fountains or beaches for different racial groups, even though the water is the same. The only function of the twin bans is to mark lesbian and gay people as inferior to heterosexual people.”