Here's a great idea for a TV drama, based on a true story. It's set in a private girls' school before the first world war. Some of the girls are enthusiastic followers of the WSPU (the Women's Social and Political Union, campaigning for women's suffrage); they pass around newspaper photographs of the Pankhursts and decorate their desks in the WSPU colours  purple, green and white. Scanning the lists of imprisoned suffragettes one day, they discover that one of their teachers has gone on hunger strike in prison and been forcibly fed. "Awed by her courage and sickened by the response of the authorities", the girls "become active supporters of the movement, distributing pamphlets and attending meetings". "The headmistress and four other teachers were given notice to leave, clearly because of their sympathy with the suffrage campaign  A term of complete disorder followed. The girls rebelled and there were near riots  several girls were suspended but broke into the school at night and painted slogans on the walls. The police were called in."

History delivers a strong finale, too, for the lucky dramatist. The girls' story was finally overtaken by the outbreak of war in 1914, when the WSPU called a halt to militancy. What layers of irony and complexity. How some of the girls must have suffered, feeling their outrage trumped and thwarted by precisely that masculine logic of violence they wanted to put an end to if they ever got to parliament. For others (such as Vera Brittain, whose teacher at a different school in Surrey had lent her books on the women's movement and taken her to a suffrage meeting), the urgency of the suffrage cause was dwarfed by the nightmare death-poetry of the war. Of course, this drama would need to be as nuanced and opaque as history itself  not merely heroic or exhortatory or cheerfully progressivist. The most interesting teacher, let's say, could be bored by the politics, finding her colleagues' enthusiasm overeager and too simplifying  she is more interested in literature and in her private life. (Virginia Woolf and Katherine Mansfield were fairly ambivalent towards the suffrage movement.)

Stories like this one, from Carol Dyhouse's useful history of girls growing up in Britain in the 20th century, ought to be the currency of our popular history and culture. What makes us addicted instead to reruns of aristocratic futility? Adelaide Clemens's performance as Valentine Wannop in the recent TV adaptation of Parade's End was a missed opportunity to deplore  there aren't many great portraits of women political activists in our literature. Valentine in the novel is abrupt, clever, robust, a suffragette, an admirer of Rosa Luxemburg and a good Latinist, and has worked  out of necessity  as a domestic servant. All the energy in the adaptation, however, was given to Sylvia Tietjens's more conventional female type, using sex for power. Clemens was exquisitely fragile and didn't seem capable of half Valentine's range; one (male) TV critic called her "pellucid and daisy-fresh"  which strikes its own Edwardian note. "Snowdrops and lilies were emblems of feminine purity," Dyhouse tells us; factory girls in the late 19th century were encouraged to wear snowdrop badges, symbolising "the white flower of a blameless life".

There's a certain twisted pleasure to be had from revisiting some of the wild and wonderful things that men (and women, too) have believed in the past about women's incapacity for education and employment. There's Granville Stanley Hall, for instance, no marginalised eccentric, but first president of the American Psychological Association and founder of the American Journal of Psychology. In 1904, in his magisterially titled Adolescence: Its Psychology, and its Relation to Physiology, Anthropology, Sociology, Sex, Crime, Religion and Education, he argued that girls were incapable of acquiring self-knowledge because their lives were ruled by "deep unconscious instincts". A girl's self-consciousness was only "the reflected knowledge that others can have of her"; girls should be protected from too much brainwork until they had crossed "the Rubicon of menstruation", then they should be taught refinement, dance and domesticity. At least one "wise, large-souled, honourable, married and attractive man" should be present on the staff of every girls' school. Every school, he wrote, has a number of girl pupils who were "little animals  infecting boys with vice".

These are twin themes running through Dyhouse's book. On the one hand, there are good girls in need of male protection; on the other hand, there are bad girls  frivolous, sluttish and out of control. In every generation since the suffragettes there has been an outcry against young girls' bad behaviour as if it were a new phenomenon  the flappers, the good-time girls, the beats, the ladettes  and every generation has looked back with nostalgia to a previous age when little girls' innocence was intact. Somewhere between the good girls and the bad girls, the bookish girls have been trying to pick their way too. For a long time, being clever  or educated, or both  could make you unfeminine without, alas, making you sexy. A high-minded commitment to women's liberation could have its puritanical aspect too. The Pankhursts demanded "purity for men" as well as "votes for women". It is a breakthrough when, in the 1960s, Linda Grant seems to manage her double life, keeping up with her notes on the English civil war by day, sneaking down to the pub in a PVC mac and mod mini-dress by night, to mix with people who drank pints and called themselves poets.

Part of the usefulness of sociology is separating the hard facts from the moral panic, and Dyhouse gives a sane account of the realities behind the scares. There weren't really ever any white slavers. Just because Girl Heaven sells sparkly pink hair slides and feathery tutus, it doesn't make everyone who shops there a hapless victim of a sexualising consumer culture. And yet, behind the pattern of youth rebellion and establishment recoil, change is real. Women's rights and opportunities in Britain now are almost unrecognisably different from what they were at the beginning of the 20th century. Dyhouse insists, rightly, on the sober incremental achievements of legislation such as the 1944 Education Act, the 1967 Abortion Law Reform Act, the 1969 Family Law Reform Act, the 1975 Sex Discrimination Act; and then there's sex education, contraception, changed attitudes to domestic violence. These orders of change have an unanswerable force  like the invention of anaesthetics, say, or the introduction of sewage and running water. It is difficult to imagine any woman choosing to go back to how things were before.

It is easier writing this kind of summarising social history about the farther -off past, and the earlier chapters in Dyhouse's book are crisper and more entertaining. As the story gets closer to home, the material seems more opaque and resistant to incisive analysis. Because some of us were there  Jackie magazine; the Brook Advisory Centres; the feminist book, Our Bodies, Ourselves; and Spare Rib magazine  we feel how complicated it all was, and how, in spite of progress, historical time as we experience it individually doesn't feel very often like a clean line leading onwards and upwards. Or, indeed, leading anywhere at all.