Gay rights activist Peter Tatchell is co-coordinating a campaign to overturn the ban on gay marriage and heterosexual civil partnerships by encouraging eight legally ineligible couples to apply to register their nuptials.
Each week from the beginning of next month until 14 December, one of the couples will either attempt to register a same-sex marriage or a mixed-sex civil partnership at a British Register Office. If they are refused, the gay rights campaign group OutRage! will mount a legal challenge.
"We believe these bans violate the Human Rights Act and are open to challenge in the High Court. Civil marriages and civil partnerships should be open to everyone without discrimination," said Tatchell.
The chief executive of the Lesbian and Gay Christian Movement, Rev Sharon Ferguson, and her partner Franka Strietzel will be the first couple to apply. Speaking to The Observer, Rev Ferguson said: "A civil partnership doesn't feel comfortable for me; it doesn't fit. We want a marriage - that is the institution we believe was divined by God and for me that is important, and I don't see why we should be denied it because of our gender.
"We have a double system and we shouldn't have. That isn't equality. Love is love at the end of the day and that should be honoured."
Liberal Democrat ministers are expected to support the legal change after their party passed a motion at their autumn conference last month calling for the opening up of marriage and civil partnerships.