A gay couple in Northampton will attempt to marry tomorrow as part of a campaign to open up marriage and civil partnerships to both straight and gay couples.

Matthew Toresen and Scott Maloney will almost certainly be turned away from Northampton Register Office and plan to take legal action over the refusal.

They are the third couple in the Equal Love campaign to apply for a ceremony they are not entitled to. Earlier this month, Rev Sharon Ferguson and her partner Franka Streitzel were denied permission to marry in Greenwich, while Tom Freeman and Katherine Doyle were refused a civil partnership in Islington.

Mr Toresen, 48, and Mr Maloney, 42, are carers and have been together for 18 years. The couple argue that marriage is worth fighting for.

Mr Toresen said: “We’ve been together now for over 18 years. Our love for each other is as valid as anybody else’s. We made a decision not to become civil-partnered because we feel that gay marriage is worth fighting for.

“It seems nonsensical to me that my two brothers are married to the women they love but that Scott and I are denied this social legitimacy and celebration.”

Mr Maloney added: “Language does matter. Marriage is universally understood as a meaningful commitment. People might say that in time civil partnerships will mean exactly the same. We say: ‘Why wait?’ Opinion polls already show that the majority of people in Britain support same-sex marriage.

“It seems to me morally right that we all should have the same compact with the state. As a gay man, I am expected to pay taxes, obey the laws and, if necessary, defend this country like everybody else. In return, I expect the state to treat me equally.”

The campaign is being arranged by gay rights activist Peter Tatchell.

He said: “A similar ban on black marriages would provoke an outcry. So why should the ban on gay marriages be tolerated?

“The bans on same-sex civil marriages and opposite-sex civil partnerships are a form of sexual apartheid – one law for gay couples and another law for heterosexual partners. Two wrongs don’t make a right,” he said.

The couple will be the third of eight couples to apply for a marriage or a civil partnership. After all eight have been refused ceremonies, they will begin legal action.