They say that no parent ever feels ready for his or her first child. But Britain certainly is prepared for the arrival of the next king or queen, no matter how Prince William and Kate are feeling. The shops are full of celebratory champagne, biscuits, cakes and souvenirs. Millions of us have already bought bunting to decorate our homes and special plates and cups for baby parties. The royal baby is on theway.

I’m a royal historian and am on standby for CNN, so I am permanently glued to my phone, carrying my television outfit in my handbag as I catch the tube back and forth to the library.

Everyone wants to know when the baby will arrive. What time? What name? But, of course, the most important question is: boy or girl? Thanks to recent changes in the law, this baby will ascend the throne, whether male or female.

I very much hope the baby is a girl.

I’ve written extensively on Queen Victoria and Queen Elizabeth and seen up close how those women, who were born when the country hoped for a male heir, made their way as leaders. They became two of our best-loved monarchs. If William and Kate give us an heiress instead of an heir, she will be better equipped to do what a monarch must do these days — shake hands, open hospitals, look regal — and as a bonus she might help drag the rest of the country a little further toward equality.

The time has come to welcome the newest British royal into the world. As Kate Middleton prepares to give birth to her highly anticipated royal baby, take a look at the little one’s situation — numerically. (Sandi Moynihan/The Washington Post)

“The English like queens,” Queen Victoria’s grandmother said on the occasion of her granddaughter’s birth in 1819. But every time a woman has come to the throne, the ministers and the populace fret that she will not be up to the job. Prime Minister Winston Churchill was plunged into misery when he heard of the death of George VI and the accession of his daughter as Elizabeth II in 1952. “She is only a child,” he wailed, even though she was nearly 26 and a mother of two children.

The motivations of kings in British history can generally be reduced to two: the quest for territory and the search for a male heir. No king was secure on his throne until he had a son, and no queen consort was ever really safe without a boy. Henry VIII went to the greatest extremes. After the pope refused to annul his marriage with Catherine of Aragon, who had given him only a daughter, Henry founded the new Church of England, ended his marriage and wed Anne Boleyn, who was pregnant by him.

It was all in vain — Anne gave birth to a girl. She was later executed. If she had borne a son, she would have been protected. And yet the unwanted little girl who sealed her mother’s doom became one of the greatest monarchs in British history: Elizabeth I.

The centuries-old habit of privileging the male heir arose because monarchs were supposed to lead their country in battle and only men were thought strong enough to do so. Elizabeth I, aware that there was prejudice against her, roused her troops to fight by telling them she had “the body of a weak, feeble woman but the heart and stomach of a king.”

Victoria is Britain’s longest-reigning monarch — Elizabeth II will beat her if she reigns until September 2015 — but no one expected her to be queen. Victoria was an only child, and her royal father, a son of George III, died when she was 8 months old. At her christening, she was called Victoria, after her mother, Victoire. As she put it, she was “the first person ever to be called Victoria.” It was seen as a ludicrous, French-derived, invented name. It showed she was just a girl, destined to be married off into a foreign royal family and never reign.

When it became clear that her uncle, King William IV, would not have any legitimate children and Victoria would be the heir, Parliament debated changing her name to Elizabeth. Her mother complained, and the name stayed. Victoria became greatly loved and finally reigned over a quarter of the world’s population. And yet she was not truly secure until she gave birth to a boy, the future Edward VII. “I do think it is rather hard on us women,” she complained of pregnancy. But the country cheered for the first proper heir born in 80 years.

Queens perhaps perform better in the role of monarch because they never take their position for granted. Many kings have failed because they believed that the public would love them whatever they did. Queens knew better.

Prince William and Duchess Kate’s second child means a reworking of who is next in line for the British throne.

A princess as rightful heir to the throne, regardless of whether a little brother comes along later, could be poised to change British society. As a lawyer friend of mine says, she will be a “constant reminder of the paradox that a female can do the top job in the country just as well as a man and yet women are still excluded from many spheres of power and influence.”

In Britain, women appear to be losing power in the sphere of government — since 2001, we have dropped from 33rd in the world to 60th in 2010 in a world survey of women in politics. Other echelons of the establishment are no better. “It is ridiculous,” says my local female vicar. “Women cannot be bishops in the Church of England — but as queen, one can be overall head of the church.”

And as the television show “Downton Abbey,” beloved by British and American viewers alike, demonstrates so well: Aristocratic titles (and the lands and power that go with them) are passed through the male line in all but a few families. Those practices are still intact. But aristocratic women have been inspired by the change in the succession law to demand parity of inheritance. A friend of mine who works in politics thinks a baby princess, in line for the throne from day one, might even encourage more women to run for office.

This eagerly awaited new princess (or prince, as I should allow for that possibility) will be delivered by the royal obstetrician, Marcus Setchell, in the private Lindo wing of St. Mary’s Hospital — exactly where Princess Diana gave birth to Prince William more than 30 years ago.

Not since William’s birth has a royal baby been so anticipated by the public. One of my dear friends is due to give birth early next week, also at St. Mary’s. She has been told that the security will be stepped up and to expect crowds of journalists around the building. Luckily, she doesn’t look very much like the Duchess of Cambridge — any new mum who does would inspire too much of a frenzy. But although she feels a little overshadowed, it is still exciting. It’s not every day that a future queen (or king) is born.

Kate Williams is the author of “Becoming Queen Victoria,” and “Young Elizabeth: The Making of Our Queen.”