Ms Thornton, now 85, and her friend Rosalie Bogner chained themselves to the public bar at Brisbane's Regatta Hotel on March 31, 1965, after they were refused service based solely on their gender.

That gesture would eventually help to open pub doors to women throughout Queensland.

"In a way, the change took place that night when the police refused to pursue the matter when it was clear we wouldn't leave voluntarily," Ms Thornton said.

Even then, though, Ms Thornton held no grudges against the landmark Brisbane pub.

"The Regatta refused us because it was illegal to serve us," she said.

"You can't altogether be very nasty to a hotel that was following the law."

After the barman, the hotel manager and uniformed police tried their best to end the protest, Jack Herbert, of Fitzgerald Inquiry fame, was the last man called in to evict them.

But even the bagman would be unsuccessful.

"Eventually he said 'so long girls, have a good night, don't drink too much'," Ms Thornton said.

"It had been established police wouldn't enforce the law, so that gave it the status of walking in front of a motor vehicle with a red flag.

"News would come through to us from various places like Townsville or down on the wharves saying Mary or Anna or whoever refused to go out of the bar last night, stayed for the whole evening and had a terrific time."

It was a game changer for a game that needed changing.

"I've heard women say that time that Queensland had made feminists of them, because it was an exaggerated form of what was happening in the south," Ms Thornton said.

The Regatta Hotel was chosen as the site of the protest because of its proximity to both the ABC studios at Toowong, for maximum coverage, and the University of Queensland at St Lucia.

It was at UQ, where Ms Thornton worked, that the plan was hatched.

"The woman academics became very irritated, because we were so few we might have been the only woman in a meeting or a conference in their discipline, they could not adjourn to the bar with the men," she said.

"Men had to make a conscious decision to sit in a ladies' lounge or they had to drop the women, or the women had to shrink away.

"One of the other women used to joke 'we should chain ourselves to the bar' and I was just the only one who didn't think it was a joke."

So did it feel like 50 years had passed since that historic night?

"Yes. Yes it does," Ms Thornton said.

"Society has changed quite a lot.

"One of the extremely good things about the bar demonstration was that it revealed there was a substantial level of support among women in particular but also among some men for opposing the unfairness to women and the failure to recognise adult women as members of the public."

However much had changed, the battle was still not over, with venues such as Tattersalls – where the Liberal National Party held an International Women's Day lunch to howls of ridicule – still not admitting female members.

"One thing to say about the difference between women's clubs and men's clubs is that it's a very different thing for men to refuse women members than women to have a women's club," Ms Thornton said.

"That's because the power positions of the two genders are so unequal. The men's club is an assertion of power, the women's club is not."