SET across the River Cherwell amid Oxford’s dreaming spires stands St Hilda’s College. Established in 1893 as a woman’s hall it only admitted men as recently in 2008. Its motto is “Excellence and Equality” and staff are justifiably proud of its achievements in promoting female voices and furthering female ambitions - things we now take for granted.

Yet it is here, on the eve of International Women’s Day, that a battle for 21st century women’s rights and freedom of speech is being fought, the like of which we have never seen before. Modern history professor and best-selling author Professor Selina Todd, who specialises in the history of the working-class, women and feminism in modern Britain, stands at the centre of an astonishing – frightening - witch hunt.

She has been branded “transphobic”, found herself no-platformed, aggressively trolled and threatened with violence. Two security guards have been drafted in by university bosses to protect her during lectures. Why? Because militant trans- activists are targeting female academics who dare to disagree with their world view; namely that sex is not a valid descriptor and should be abolished as a legal identity, to be replaced by self-described gender.

“The focus of my research is women’s history,” says Prof Todd. “I believe in robust evidence and have come to the conclusion that I agree with the legal and traditional definition of men and women according to their biological sex.

“Throughout history women have been treated differently because of their actual or potential roles as mothers. They have been discriminated against in ways that men are not; biology matters. If we don’t define woman and men as separate sexes, then how do we categorise them?”

Prof Todd, who was born in Newcastle and state educated, looks like an academic straight from central casting; charismatic, energetic, slender as a letter opener with neatly bobbed hair, she is the very opposite of strident. When she speaks, it is with soft urgency, measured reasonableness.

Her study is lined with bright cards offering her support, bearing legends such as “don’t let the bastards grind you down”, and a picture of the suffragist sculpture of Millicent Fawcett in Parliament Square which sees her holding the banner “Courage calls to courage everywhere”.

“I am not transphobic,” she says matter-of-factly. “I have students who are transgender and I have great sympathy for the difficulties they go through as they grapple to work out their gender identity.

“Everybody has the right to be who they want to be and I completely understand there’s a huge amount of pain and hurt around this whole subject. But I passionately believe in free speech and social media name-calling and hurling of abuse are no substitute for careful, considered debate about how we negotiate women’s rights and transgender people’s rights.”

Ominously, free speech is being curtailed. Last week transgender campaigners demanded that her invitation to speak at an event being held as part of the Oxford International Women’s Festival be rescinded or they would boycott the occasion and mount a protest outside.

It was the evening before the event; the organisers quiesced. This may sound like a storm in a scholarly teacup, but make no mistake, it is a full frontal assault on wider democratic freedoms. This week former Home Secretary Amber Rudd was also no-platformed by Oxford university students, who canceled the UNWomen Oxford society event she was due to speak at without telling her.