Danny Kruger is MP for Devizes.

The politics of sex and gender is a minefield, made more dangerous by a great confusion of language. But at root the issues are straightforward, and the Government should gently but clearly assert the truth. Two facts need stating.

First: gender is no business of the state. Gender is the complex, psycho-social construction we build on the foundation of our immutable sexual biology. For most of us, our gender conforms to our sex. A small number of people, however, feel uncomfortable in their biological sex, and adopt a different gender. This is their right. If biological males wish to live as women, or biological women as men, in a free and tolerant society they should encounter no objection.

Second: sex is the business of the state. The distinction between maleness and femaleness, the essential qualities written into our biology, is a fundamental building block of society. For someone to cross the border between the two, formally to assume the legal status and the rights of the opposite sex, is a big deal, properly requiring the permission of government.

This permission is available through the (misnamed) Gender Recognition Act 2004, which allows people to be recognised as legally belonging to a different sex (nothing to do with gender) from their biological one. Recognition consists of the award of a (misnamed) Gender Reassignment Certificate (GRC). To get a GRC you need a diagnosis of the medical condition known as gender dysphoria, defined as acute psychological discomfort arising from the sense of inhabiting the wrong sex, plus a period of living as a man (if a biological woman) or vice versa.

Some trans activists, backed by the LGBT lobby group Stonewall, are conflating these two facts, by seeking a change to the GRA to let people change their legal sex as easily as they can change their gender. They argue that people should be allowed to ‘self-identify – to receive a GRC simply on the basis of asserting their desire for one, with no need for a gender dysphoria diagnosis or a ‘lived identity’ period.

These activists won a victory in 2016 when the Women and Equalities Select Committee recommended reform of the GRA to allow self-ID and the Conservative Government of the time agreed to a public consultation. That consultation closed in late 2018, but our turbulent politics since then meant that the nettle has never been grasped. It appears the new Government is now preparing to respond to the consultation and state its position on self-ID and the GRA.

I fervently hope that ministers will confirm the status quo. They should also issue clear guidance that service providers should be allowed to establish single-sex facilities and services based on birth sex, assuming this is a proportionate means of achieving a legitimate aim.

But though the thought of a predatory man simply claiming a GRC and gaining access to female-only changing rooms, hospital wards and prisons is troubling, to my mind the argument against self-ID is not the immediate practical one about single-sex spaces. The case for a high bar for anyone crossing the line between legal ‘man’ and legal ‘woman’ is more fundamental.

The distinction between the sexes is real. Preserving this distinction is to defend the grammar of our common life, and to uphold the essential point that our society and legal order are founded on the truth as we understand it. To concede the claims of the extreme trans lobby – that sex is not fixed in biology, but simply ‘assigned’ at birth – is to sell the pass. We will be in Wonderland, or in 1984, where truth is what the people in charge decide it is.

We are arguably already there. Lewis Carroll described a child perplexed by the antics of grownups living in an alternative reality. The Tavistock NHS Clinic, where children are told they can be the sex they want to be and given puberty-blocking hormone treatments, is our Wonderland.

Debbie Hayton, the courageous campaigner against this madness (and a transwoman herself), quotes Orwell: ‘If thought corrupts language, language can also corrupt thought.’ Such is our intellectual corruption that front bench Labour politicians can argue that sex (not gender) is a social construct. Liz Truss, the Equalities Minister, should stand against this, and unequivocally say what is true. Our party, and the country, will applaud.