In 2018, Britain didn’t only tear itself apart over Brexit; it split over another issue, brewing for years: the rights of transgender people.

The faultline finally cracked open in early autumn. Over the summer, the government had launched its public consultation into how to update the Gender Recognition Act, the 2004 law that governs how trans people can change their gender legally. The plan was to make it easier.

Just four days later, rows in the press and across social media spilled out onto the streets. Anti-trans feminist protesters disrupted London Pride by charging the front of the parade exclaiming that trans rights “erase lesbians”. It took only a month for this isolated protest to atomise into a national backlash.

Stickers were plastered around public places: trains, toilets, monuments, the offices of Britain’s largest LGBT charity, Stonewall. The stickers, produced by a radical feminist group called Liverpool ReSisters, said, “Women don’t have penises,” complete with a line drawing of one. The penis doodle quickly became the symbol of those seeking to exclude trans women.

Trans-critical feminist groups sprang up. Activists distributed leaflets calling on people to respond to the consultation and resist any changes to the law. In retaliation, LGBT activists affixed posters around Manchester’s Gay Village making clear that anti-trans campaigners were unwelcome.

Legal cases erupted. Conspiracy theories spread. Speakers were booked and then dropped. Newspapers filled their comment pages with, predominantly, criticism of trans people, trans rights, and what they called the trans “lobby”. Even the Guardian newspaper, previously hedging its bets by giving space to both sides, said in an editorial — its official position — that trans rights “collide” with women’s rights. It divided its own newsroom.

A culture war was alight. At the centre of the fight was one concept: self-declaration (also referred to as self-ID). This is a simplified system by which trans people can have their gender legally recognised, without some of the existing requirements such as having to have a psychiatric diagnosis of gender dysphoria, having to be approved by a panel of experts, or having to live in the declared gender for two years first.