The 50th anniversary of the first Women’s Liberation Conference in Oxford was planned as a celebration of social struggle and triumphant survival. But on Saturday morning the event quickly turned into an angry and full-throated demonstration of the ongoing arguments inside the movement.

The alleged “no platforming” of feminist historian Selina Todd the night before the conference prompted loud protests from the packed hall at the former site of Ruskin College, the spot of the original meeting in 1970. “This is cowardice. How can we do this to a woman who has worked all her life on behalf of other disenfranchised women?” asked Julie Bindel, the radical feminist writer.

Organisers said that Todd had not been banned from the conference, but was asked to give up her short “thank you” speech slot on behalf of the Oxford University history faculty in response to a boycott threat from other speakers.

Author Lola Olufemi, a billed panellist who had pulled out of the event when she learned of Todd’s involvement, said in a statement that she felt the conference planners had not done enough to investigate Todd’s alignment with the Woman’s Place UK group, which she regards as “transphobic”. “I have seen first-hand how middle-class white women with social capital have used their gatekeeping power to harass trans people, threaten them with defamation, actively work to curtail their rights, refused to extend solidarity, and then claim victimhood,” she said, explaining why she withdrew from the event.

Woman’s Place UK is pushing for government ministers to consult more widely about changes to the Gender Recognition Act, which would allow people to legally self-identify as a man or a woman without medical approval. It rejects accusations that it is transphobic and trans-exclusionist. Its founders say it aims to “ensure that women’s voices are heard and our sex-based rights upheld”. However, critics say it is trying to limit the rights of trans people.

Todd was re-invited into the hall after a show of hands in favour from a large majority, among them at least 15 women who were at the 1970 conference, including Sheila Rowbotham, Sue O’Sullivan and Sally Alexander, the activist played by Keira Knightley in the new film Misbehaviour.

Facebook Twitter Pinterest BBC presenter Samira Ahmed spoke at the conference saying she ‘never thought she would have to make a sex discrimination pay claim’. Photograph: Yui Mok/PA

Todd did not appear at the morning session, but a statement issued in criticism of her treatment and distributed around the hall said: “Selina Todd supports the right of women and girls to same-sex spaces (such as refuges). This is enshrined in law. Her opponents believe the law should be changed. They aren’t willing to engage in respectful debate with those who disagree, preferring to silence feminists.”

The text of Todd’s undelivered speech to the conference opened with thanks to Ruskin College, the trade union-sponsored educational establishment now based outside the city in Headington, as the place where her parents had met in 1967. Of feminism’s future, she would have said: “We’ve got far to go and it’s easy to despair. But history reminds us feminism never starts from a good place: it is borne from oppression.”

The BBC presenter Samira Ahmed also addressed the conference, saying she was concerned by the “no platforming” of Todd as she believed it was important to listen to each other.

Speaking about her recent battle for equal pay, one of four key demands back in 1970, she said: “I never thought I would have to make a sex discrimination pay claim. I thought it would all be sorted.”

Other demands of the original conference were improved education, 24-hour nurseries, free contraception and abortion on demand.

The mood of the 40th anniversary events was comparatively warm and nostalgic, according to accounts. The 50th birthday row, it seems, was much more in keeping with the fiery debate of the first conference, which had been called for by Rowbotham and was initially focused on women’s collective history until it was realised so little had ever been recorded. Instead it turned to contemporary issues, and in a then radical twist, men ran a creche so that any mothers were free to speak.

Alexander, who as a student helped set up the first event, said she recalled it as “episodic and chaotic”. “We had expected 100 women and 600 came,” she said, going on to praise the calm manner of Sue Vickery who chaired the 1970 event. “We were feeling our way,” she said, “and borrowing the vocabulary of other movements, like the civil rights campaign. We used the word ‘woman’ then with a sense of enthusiasm and pride. The phrase Women’s Liberation raised fear then for ourselves and for others, and sometimes it still does.”

Seven other national Women’s Liberation Movement conferences followed the initial Oxford event in 1970. Further central demands were added along the way, including legal and financial independence for all women, an end to discrimination against lesbians, freedom from intimidation by the threat or use of violence or sexual coercion, either in or outside marriage, and an end to laws and assumptions that shore up the male domination of women.

Most pertinently – though it had different significance then – a controversial decision made at the Birmingham conference put “the right to a self-defined sexuality” at the top as a preface to all the other demands.