The City of London Corporation is defending allowing trans women to use female spaces at Hampstead Heath ponds, after it was accused by a feminist charity of compromising “privacy, dignity and a sense of safety”.

The charity Sex Matters is challenging the Square Mile authority’s rules the grant access to facilities at the North London swimming ponds in court on gender identity rather than sex in the High Court.

In June, the Corporation confirmed the Kenwood ladies pond would be accessible to transgender women, whose biological sex is male, while the Highgate men’s pond would be open to transgender men whose biological sex is female. The City of London confirmed the mixed pond would remain open to all.

In its written submissions, Sex Matters argues the policy violates the Equality Act 2010 and that allowing access to both biological women and trans women into the facilities “indirectly discriminates against women” by allowing biologically male users access on the basis of gender identity.

The charity said that for women using the ponds, “the particular disadvantage is the greater risk, compared to men, of experiencing compromise to their privacy, dignity and/or safety as a result.”

The City of London argued that the admission arrangement at the Hampstead bathing ponds is lawful under the Equality Act 2010.

“There is nothing in the Equality Act 2010 that supports the contention that trans-inclusive arrangements are inherently and necessarily unlawful,” it said.

Supreme court rules on gender identity

The case follows a Supreme Court judgment handed down in April last year in which the judges unanimously ruled that a woman is defined by biological sex.

Maya Forstater, chief executive of Sex Matters, said the charity “is asking the court to make a substantive judgment on whether any version of the City of London’s “trans inclusive” rules at the ponds are lawful.”

“We will also argue that allowing men who identify as women to use the Ladies’ Pond is a form of sex discrimination towards women, because their privacy, dignity and safety is compromised,” Forstater added.

A spokesperson for the City of London Corporation said: “The Supreme Court clarified the legal definition of ‘sex’, but it did not require all services to become single‑sex, nor did it prevent trans‑inclusive arrangements.

“Our focus is, and always has been, on providing a safe, respectful, and well‑managed environment for everyone who uses the ponds. We are confident that our approach is lawful, proportionate, and appropriate.”