Taking to X, Mrs Braverman wrote: “I have no problem with what he wears or what he does in private.”

“But he is a man. And it is not transphobic to say so,” she declared.

“It is insulting and inappropriate to the 1.5 million women who suffer with endometriosis for him to have been appointed to speak for them.

“Today I have written to Endometriosis South Coast to urge a reconsideration of this appointment,” the Reform MP said.

Steph Richards previously served as the organisation’s chief executive but departed in 2024 amid objections from women’s rights campaigners who deemed the leadership “insulting”.

They also founded TransLucent, which works for the “gender-diverse community in the UK”.

In her letter, Mrs Braverman wrote that: “Endometriosis is a complex and debilitating condition that affects around one in ten women.

“It is rooted in female reproductive biology, and the women who suffer from it often endure years of pain, misdiagnosis and neglect.

“Their voices, and their first-hand experiences, must be central to any credible effort to improve understanding and support.”

She said it was therefore “remarkable” that the charity would appoint someone who was “without female anatomy or experience of this disease, to speak for those whose suffering is defined by their sex”.

“This regressive decision erases women from their own health issues, replaces lived female experience with male self-identification and silences the very people your organisation claims to represent.

“At a time when women’s rights are under sustained attack from a warped gender ideology, it is appalling that a charity would choose to side with that agenda rather than with the women it exists to serve,” she wrote.

Mrs Braverman’s comments echoed those made by Rosie Duffield, the independent MP for Canterbury, who described Steph Steph Richards’ “inappropriate” appointment as making her “really uncomfortable”.

Endometriosis South Coast has defended its decision, maintaining Steph Richards was selected on the basis of merit and dedication to raising awareness of the condition at the policy level.

The charity clarified its new parliamentary envoy holds a volunteer position and does not occupy a senior role or speak directly on behalf of those affected by the disease.

A spokesman rejected the premise that only women experience endometriosis, calling such a claim “scientifically inaccurate”.

“It affects people of all genders, including trans men, non-binary, and intersex individuals,” the charity stated.

The organisation argued that effective advocacy does not depend on personal experience of a medical condition.

It insisted this principle applies throughout healthcare, policymaking and the voluntary sector.

Steph Richards has previously dismissed outrage following the appointment with the charity as “transphobic”.