I can still remember clearly the first time I heard about Charles Keidan and Rebecca Steinfeld.

We were driving through the misty Highlands to spend Christmas north of the border and they popped up on the radio being interviewed about the very early days of their High Court challenge to the government’s position on civil partnerships.

Currently under UK law, all couples have the right to marry, however only same-sex couples are able to form civil partnerships, a hangover from the way that same sex marriage was introduced in 2013.

As someone who has remained happily unmarried, but in the same relationship for 38 years (with Alastair Campbell) with three grown up children, this seemed like a glaring injustice. Within ten minutes of tracking down Charles Keidan (incidentally a local boy who grew up in Swiss Cottage) on Twitter from the middle of Glencoe no less, I was signed up to support their campaign and steering group.

Four years on I can proudly say that this young couple, who have managed to have two children and hold down demanding careers while challenging the government in and out of the courts, have made legal history.

In June they finally won their legal battle when the five judges of the Supreme Court ruled that the government’s refusal to allow opposite sex couples to have civil partnerships was ‘incompatible’ with human rights law. And this week the government conceded that the best way to guarantee equality, legal and financial protection to all couples was to extend civil partnership unconditionally.

Why does this matter so much? Well, marriage isn’t for everyone. There are currently around three million couples who live together without being married, 39 per cent of whom have dependent children. In fact, we are the fastest growing family “type”

Yet a recent survey suggested that two thirds of these co-habitees mistakenly believed they were protected by the mythical concept of a “common law marriage “, which could have serious implications for them and their children in the case of family breakdown, bereavement, inheritance and pension rights.

Of course, not all will take up the option a civil partnership, but this week’s decision at least provides an equal choice of a modern social institution, that provides the same legal protections as marriage without any of the historical (and patriarchal) trappings that go with traditional matrimony.

However, none of our 100,000 plus supporters are cracking open the champagne yet. The government still has to spell out how and when it plans to bring forward legislation in a parliament weighed down by Brexit; there are mutterings about further consultation on the detail.

But this week marks a turning point – the government could have chosen to deal with the legal incompatibility by abolishing civil partnerships altogether – a backward step which would have involved taking rights away from gay couples, a significant minority of whom are still opting for civil partnerships rather than marriage.

But they opted to take a positive step forward. Alastair and I haven’t completely committed to taking the plunge yet when the law is finally changed. My involvement in the campaign was always as much about putting right a wrong and ensuring choices existed for younger families than ours, but my daughter is already planning the party and, whether we do it or not, it feels good to have been part of a historic and progressive moment.