Do I detect a tectonic shift?

The newspapers are suddenly full of women fighting back. One widely reported protest was triggered by billboards advertising a diet drink. The yellow posters displayed on the London underground featured a toned and super-slender, bikini-clad model. She stood pouting, legs parted, breasts pushed up beside a written question: "Are you beach body ready?"

Many of the posters were defaced with graffiti protesting that every body on a beach is beach body ready. More than 270 complaints were received by the Advertising Standards Authority, which is investigating whether the ad was socially responsible.

A spoof poster was produced. It showed three women with sizeable bottoms standing smiling in front of this slogan: "Yes. We are beach body ready." Last weekend, dozens of women and some men braved cold weather to stand in protest in Hyde Park wearing bikinis and beachwear. The advertisements have been removed.

Will the action be effective in the long run? It's a fact that, while people buy the products, manufacturers will try to continue this sales technique. There is even an argument that advertisers court controversy precisely in order to attract more attention to their product. The beach body model, Renee Somerfield, expects a boost in her bookings.

But, because of the public reaction, a message also goes out to girls everywhere that women are more than their sexuality; that to be beautiful and acceptable their body doesn't have to conform to one shape or size. So we can celebrate the demonstration of intolerance. It tells us a vociferous section of the female population is saying: "That's enough. We're not taking any more."

For those who think women are having a sense of humour failure I can recommend a video of artist Jack Willis Thomas showing work he exhibited in New York last month. His exhibition was entitled Branded. It displays one advertisement a year from 1915 to 2015. The slogans have been removed the better to show how white women have been depicted throughout the century.

In pre-war advertisements, they are having their coffee poured by black servants. During the war years, the images change. Women are out of doors working. They're farming crops, wearing trousers or they are in military uniform. Men are cheering them on.

Then the war stops, the economy requires them to go back to the kitchen and the misogyny starts. Not only are the adverts sexualised, in one a woman in her underwear is being dragged along the floor by her hair. In another, selling cigarettes, the woman is sporting a black eye and a look of tolerant resignation. There's one of a woman in a straight-jacket and another of a woman in a bikini on a beach, sitting in a giant frying pan. The message seems to be that you can take the girl out of the kitchen, but not for long.

And then there is what looks like a contemporary shot of a beautiful young woman in a pink dress. She is bent double in the act of removing a man's cowboy boots. Her bottom is toward his face. Could it be the one for 2015?

All of these images have been used to sell products. All have been found acceptable in their day. It's hard to believe, in retrospect. My generation has been walking past some of them or flicking past them in magazines. We've grown so accustomed to them that it's only when looking back that we feel outraged.

Thankfully, some young women today are more clear-eyed about the insult.

Take 23-year-old Poppy Smart, a digital marketing co-ordinator from Worcester who never imagined her daily walk to work would propel her into the national news.

Poppy has suffered from anxiety since her teens. She started a new job a couple of months ago in an office that was a 15-minute walk from home. It was a walk she enjoyed until some building workers spotted her and started to wolf whistle every time she passed by. Then they started to make comments about her bottom after she had passed.

She began to dread the ordeal, to button up her jacket even in hot weather. She thought about changing her route but couldn't do so without adding 10 minutes to her journey. She suffered the discomfort until one of the builders stepped onto the pavement and blocked her way. Another was sniggering and a further six or seven stood by watching.

When Poppy got to work she rang the police.

No one was arrested but the men were spoken to. One of them told a newspaper that Poppy should have seen the cat-calls for the compliment they were intended to be.

Should she? Of course not. Nor should she or any other woman have to walk past demeaning advertisements.

This objectification of women is all part of a culture that, at its worst, can lead to sexual assault from men who feel entitled to help themselves.

They leave their victims feeling violated and so ashamed that they keep it a secret; no longer, however, if some female students at Oxford University get their way.

After being sexually assaulted, student Ione Wells launched an online #NotGuilty campaign. Her message is that assaults are never the fault of the victim. In the student newspaper, Cherwell, she published an account of how her 17-year-old-attacker dragged her to the ground and smashed her head against the pavement. She also wrote to him to say: "I am a daughter, a friend, a girlfriend. You will not win."

A second student then revealed an attack she had hidden, even from her own consciousness, for months. She'd been tied up, raped by two men and dumped in a bin.

It was reading reports of all of these protests in the space of a week that alerted me to an important shift in public opinion. Women are no longer just thinking about protest or talking about protest. They are taking action; fighting back.

It is so very welcome, and not before time.

We can see from the work of Jack Willis Thomas that the misrepresentation of a woman as a piece of meat, an object of desire, a commodity to be enjoyed like a cigar or fine wine did not come about naturally. It was invented by men out of political and economic expediency. The images stuck because they cleverly tapped into sexual desire and the attraction of power.

And, as a woman who grew up under its spell, I'll hold up my hands and admit it took us too long to see through it and to fight back; not so today's generation of young women. I hope these examples of fighting back are just the beginning of a seismic shift in attitude that will shake up the world.