06/02/2013 07:28 GMT | Updated 08/04/2013 06:12 BST

After Gay Marriage, the Next Step Should Be Heterosexual Partnerships

Yesterday's vote in the House of Commons for gay marriage marks a historic moment in the progress of equality in Britain. With the large Commons majority of 225, the elected representatives have spoken, and the House of Lords has no grounds for resistance.

Britain has joined other progressive states, including Sweden, Denmark, Canada and Belgium, in giving gay couples an equal right to marry as that enjoyed by heterosexual couples.

For once, a large majority of MPs (if not a majority of Tory MPs) fell into line with progressive public opinion (62% in favour to 31% opposed in a pre-Christmas poll) - as they've failed to do on issues ranging from drug laws to renationalising the railways.

I'm proud to say that the Green Party has been at the forefront of campaigns for LGBT equality. In Brighton, where the Green Party is running its first council in a minority administration, we hosted the council's first LGBT conference in 2011, holding workshops and presentations from council officers and local community organisations, whose work has benefited the city's LGBT community.

Just last month, lesbian, gay and bisexual pressure group Stonewall named Brighton and Hove City Council the most LGB-friendly local authority in the country, and the council has supported such events as the International Day Against Homophobia, Biphobia & Transphobia, and the Transgender Day of Remembrance. (Our sister party in Scotland has also been at the forefront of campaigning for gay marriage.)

Our Green MP Caroline Lucas was also leading in yesterday's debate, making the point that now there's a further equality issue be tackled. MPs have acknowledged that civil partnerships don't meet all couples' needs - now they need to go a step further, and acknowledge that marriage doesn't meet the needs of all heterosexual couples.

There can be no logical grounds for denying heterosexual couples the option of civil partnership as created under the Civil Partnership Act of 2004 - a simple, legal step that can resolve issues around child custody, inheritance, pension rights and a whole host of other issues.

There are many people opposed to the historical and political associations of the institution of 'marriage' - some of the same associations that have left some gay couples seeking the marriage option.

In France, the equivalent of civil partnerships have been available to gay and straight couples alike since 1999, and in 2009, some 95% of those taking up the pacte civil de solidarite (Pacs) were heterosexual. There are now two couple entering the civil partnerships for every three getting married.

And while we are talking about the institutions of 'coupledom', there's a further important issue to be addressed - an issue of education and understanding. There is no such thing as 'common law marriage' in Britain, yet it's a phrase that you'll hear bandied about regularly, and a false belief in its existence has had severe financial and emotional consequences for many.

There's also a recognised problem around inheritance when an unformalised partnership ends with the death of an intestate partner - a lot of work has been done around this issue; now's the time for action.

In 2004, 13% of men and 12% of women were cohabiting in England and Wales, and 1,278,455 children were dependent on a cohabiting couple. This affects a lot of people - and even if we complete the circle of equal marriage and civil partnerships it is still going to affect many.

We live in a world of many different family arrangements - what we need to do is to give couples a range of legal tools (and full understanding of them) so that they can have security and certainty about the shape of their family life, and real choices about how to construct it. We took an important step forward yesterday - now we need to complete the work.