The ancient rules of royal succession have handed men the balance of power for hundreds of years.
Women have still managed to accede to the throne, even becoming the country's longest-serving monarchs - Queen Victoria and the current Queen Elizabeth II.
But now, with the 15 other Commonwealth nations where the Queen is head of state backing the modernisation, first-born royal daughters in direct line to the throne will no longer be leapfrogged by their younger male siblings.
The radical shake-up to the way the monarchy works was spurred on by the marriage of the Duke and Duchess of Cambridge earlier this year.
If William and Kate's first child happens to be a girl, she will automatically become queen one day, regardless of whether she has a younger brother.
Yet it is still likely to be many years before another female monarch takes to the throne.
The Royal Family already has two generations of kings-in-waiting and the Queen is celebrating her Diamond Jubilee next year and in good health. Her own mother, the Queen Mother, lived to 101.
Heir apparent the Prince of Wales is next in line and then there is William, who has still to fulfil his regal duties before any child of his takes over.
Even then, William and Kate might have a son, meaning the nation would wait even longer to see the first royal daughter to benefit from the rule change.
But the fact that the laws will be updated brings an essential equality of the sexes to the British monarchy which did not exist before and which will in time change history.
As for the current members of the Royal Family, there will be no switching around.
Any new law is not expected to be retrospective - the Princess Royal would still be placed below her two younger brothers, the Duke of York and the Earl of Wessex.
For some, the changes do not go far enough.
Republic, which campaigns for a directly-elected ceremonial head of state, said they still failed the "equality test".
Campaign manager Graham Smith said: "In practice, it simply means that the eldest child of one family is preferred over all others. Inequality is therefore further entrenched in the system."