Tomorrow is the anniversary of the flour-bombing of the 1970 Miss World. What happened to the women behind the protests?

Forty years ago tomorrow the televised Miss World beauty pageant was hit by tomatoes as well as smoke-, flour- and stink-bombs. Millions of TV viewers watched the first headline-grabbing act of the newly formed Women's Liberation Movement (WLM) as they chanted: "We're not beautiful, we're not ugly, we're angry." Born that summer, the movement flourished for a decade, and sparked hundreds of feminist groups all over the country.

In 1970, Miss World was as much of an institution as the Queen's Speech or Armistice Day on British TV, but the protest at the Royal Albert Hall in London marked the beginning of the end. Dropped by the BBC at the end of the decade, it is now available only in the more obscure parts of the multi-channel world, although it thrives overseas. "It seems incredible that it was on TV," says Sue Finch, one of the protestors. "It really was a cattle market."

Jane Grant, who had been at the first WLM conference at Ruskin college in 1970, helped to organise the protest. She fondly remembers the detailed planning, and stresses that the focus was on the show's host, Bob Hope, a Hollywood comedian with a reputation for reactionary and racist gags. "It wasn't about messing things up for the women in the competition or causing harm in any way."

Sarah Wilson, a veteran of 60s revolutionary politics, was chosen to start the protest. "When Bob Hope was going on and on with terrible, grotesque stuff, I got up and swung my football rattle. It seemed ages before anybody responded – people were lighting their cigarettes to ignite the smoke bombs – but then I saw stuff beginning to cascade down."

From her position in the balcony, Jenny Fortune saw the signal. She had come with a busload of women from Essex University. "We threw leaflets, bags of flour and smoke bombs – the Albert Hall was covered with smoke and leaflets. It was pandemonium."

One woman who had been watching Miss World on TV at home nearby actually raced out of her house and joined in.

Fortune was among several women to be arrested. Finch, who was nine months pregnant, was seized by bouncers "and literally bounced out". Grant was held in a room in the hall until about midnight.

Four of the women decided to conduct their own defence, including Jenny Fortune and Jo Robinson. Robinson was heavily pregnant and repeatedly used her right to ask for a loo break, which eventually annoyed the magistrate. When she threatened to relieve herself in the court, a fracas ensued. The women on trial were rearrested and spent the night in Holloway prison, and ended up being fined for various offences. Nevertheless, Fortune describes the experience as an "epiphany . . . It was the most fantastic feeling: facing your fears – and my fears were my family's fears: if I stopped being a nice middle-class girl, I'd get into bad trouble."

Some of the women continued campaigning. Fortune became active in the Claimants Union and in housing politics in east London – campaigning for women's right to housing in their own names. Sue Finch became a peace campaigner, and earlier this year was among demonstrators who closed down the Aldermaston weapons base. The movement is part of the current feminist renaissance. Some of the Miss World veterans will be joining a Reclaim the Night march – started in the 70s, revived in the 00s – against violence and sexism in the streets.

Not everything has marched on, however. This week saw another anniversary: 40 years ago, the Sun launched its Page 3 parade of naked women. Yesterday, in that paper feminist Germaine Greer wrote in support of the feature. The women's liberation movement changed a bit of the world on 20 November 1970 – they didn't change everything.

• This article was amended on 19 November 2010. In the original, Jane Grant was said to have been one of four women who conducted their own trial defence. This has been corrected, as she was not put on trial.