Fourteen years ago last month, the House of Lords adopted an amendment to the Civil Partnership Bill which was passing through Parliament. The amendment would have extended the right to form a civil partnership beyond gay couples to adult family members who lived together long term.

Peers argued that, if the government was creating an institution for those ineligible to marry (which gay couples then were) which provided them with legal and fiscal rights and safeguards, then why should a pair of unmarried siblings, for example, who live together all their lives – perhaps taking in, and caring for, relations in old age – not benefit also? Civil partnerships, after all, unlike marriage, were to contain no legal expectation of a sexual relationship. So why the discrimination?

The amendment was overturned in the Commons which thought it all too complicated.  The injustice against blood-related cohabitants was widely acknowledged on all sides, but this could be sorted out at a later date. The main pre-occupation now was ensuring equality between gay and heterosexual couples and that was to remain the sole purpose of the Civil Partnership Bill. It was to mimic traditional marriage for gay couples.

Fourteen years on, and despite many attempts during the passage of various bills to right this injustice to blood-related cohabitants, no action has ever been taken. Gay couples can now have a same sex marriage, or they can opt to mimic same sex marriage by forming a civil partnership. Heterosexual couples can marry and might also get the option of mimicking traditional marriage with a civil partnership instead. (That’s if the government gives in to the pressure created by last month’s Supreme Court ruling that it’s a denial of a heterosexual couple’s human rights not to allow them a civil partnership even though they are free to marry which would give them all the same rights.)  Meanwhile, blood-related cohabitants remain the only group with no access to any legal safeguards at all.

As one half of a mutually supportive sibling partnership – my sister and I have lived together for decades – I have followed this debate with hawk-like attentiveness.  Over the years I have met and corresponded with many people affected by the injustice. The rights that are denied to those who are not allowed civil partnerships include inheritance tax exemptions, the right to inherit a tenancy and survivors’ pension rights. In the most distressing cases, the bereaved survivor of a long-term, platonic partnership is forced to sell the joint home on his/her partner’s death because only married couples and civil partners can inherit their partner’s share of the jointly owned property free of tax.

Round the corner from me and my sister here in South London live another pair of sisters, now in their late seventies, who live in the house in which they grew up. The quintessential ideal neighbours. When, many years ago, their next door neighbour died young, leaving two small children with a father who had to work permanent night shifts, they took the children in for him and brought them up. I bump into the sisters when they drop off the shopping to a pair of brothers in our road, who also live together and are too old and frail to get out.

When the first sister dies – because they are siblings and not sexual partners – the other will have to sell up and move out. It’s the same thing for the brothers they visit with the shopping. Same with me and my sister too – and especially unfair to my sister if I die first, since she has sacrificed much to live with me, helping me, when I was faced with single parenthood, to bring up my daughter from birth to adulthood in a stable and loving home.

I first started writing letters to the government about this in 2008, at about the time the splendid Burden sisters, Joyce and Sybil, who lost their case on this issue at the European Court of Human Rights, left off. “Why can siblings have neither civil partnerships nor any of the rights that go with them?” I asked the government. “Because civil partnerships are intended to mirror marriage for gay couples who can’t marry” came the answer.

When same sex marriage came in, I wrote again. “Now that same sex marriage is allowed so there is no longer any need for civil partnerships to mimic marriage, why can’t cohabiting siblings have a civil partnership, or any of the rights that go with them?”  Four months later this was the reply: “Because civil partnerships were brought in for same sex couples at a time when they could not marry, so blood relations were barred, just as they are from marriage”.  Ah, right. I see. That explains it then. Thanks.

Then, some four or so years ago, I got very excited when Conservative MP Tim Loughton and the “Equal Civil Partnerships Campaign” came along, with their plan to pressurise the government into opening civil partnerships to all. “Wow, terrific! I said to them. To all?”. “Well, er, no, not actually to all. Just to all opposite and same sex couples. All loving couples”.  Blood-related partnerships would still be exempt. “What?” I said. “You mean the government should turn an institution set up to provide rights to those ineligible for marriage into one which includes all those who are eligible for marriage and excludes only all those who are not?”  Yes, in a word. That’s what they think.

Meanwhile, hope for blood-related cohabitants comes in the form of the senior Conservative peer and official historian of the Conservative Party, Lord Lexden, who has taken up our cause. His own bill, due for its second reading in the House of Lords on 20th of this month, would extend eligibility for civil partnerships to siblings aged over 30 who have lived together for a continuous period of 12 years.  This would not solve the whole problem – other family members who should not be exempt still would be – but it would be a hugely significant start. Most importantly, it would remove the presumption of a sexual relationship as the – now wholly invalid – basis for the right to form a civil partnership.

My most recent letter to the government was to the “equalities minister” Penny Mordaunt. In it I asked her about the government’s arbitrary discrimination against blood relations and outlined the hardship it causes. I also noted that Lord Lexden’s bill was coming up for its second reading. I ended my letter thus:

“I very much hope that you can reassure me that you recognise that stable, devoted, platonic cohabiting partnerships are no less worthy of fair treatment under the law than sexual ones, that you agree that the way in which they are currently treated is unfair and that you are open to ideas of ways in which the government might help. The worst possible outcome, it seems to me, of the forthcoming review of the future of civil partnerships would be that it becomes an opportunity wasted for this glaring injustice to be addressed”.

That was more than a month ago. No reply as yet from the government of “the party of the family”.