Prime Minster David Cameron announced back in October 2011, that the British monarchy's archaic system of male-preference primogeniture was to be overturned.

At a meeting of the leaders of the 16 Commonwealth countries in Perth, Australia, a motion was unanimously agreed to amend the succession rules.

Why now?

There have been at least 11 attempts in the past to try and change the order of succession, but conservative opposition meant that they never went far.

However, with the marriage of William and Catherine in April 201, the issue was brought back into focus.

David Cameron referred directly to the couple in his speech to Commonwealth leaders, saying the current rules were "outdated".

"The idea that a younger son should become monarch instead of an elder daughter simply because he's a man... this way of thinking is at odds with the modern countries that we've all become," he said.

A modern breakthrough

The planned change will end centuries of tradition and law, and so will mark a turning point in the British Royal family’s history.

However, more than a year and a half later, the proposals haven’t become law yet.

The 16 Commonwealth countries have approved it in principle, and discussions are on-going in Parliament.

However, several pieces of complicated historic legislation will need to be altered

Why is it taking so long?

In addition to the Act of Settlement 1701, many other laws will have to be altered, including the Bill of Rights 1689, the Coronation Oath Act 1688, the Acts of Union and the Royal Marriage Act 1772.

Each of the 15 other Commonwealth members, which Queen Elizabeth II is the head of state of, would then have to amend their own legislation.

Those nations are Antigua and Barbuda, Australia, Bahamas, Barbados, Belize, Canada, Grenada, Jamaica, New Zealand, Papua New Guinea, St Kitts and Nevis, St Lucia, St Vincent and the Grenadines, Solomon Islands, and Tuvalu.

It’s unclear how long this will all take, but according to David Cameron, the changes will apply to descendants of the Prince of Wales retrospectively.

So basically, even if a royal girl is born before they sort this out, the changes will still apply to her.

What next for royal women?

Once the legal small print is ironed out, the order of succession will in future be determined by the order of birth.

And the immediate impact will affect other royal women too.

The Princess Royal, the Queen's daughter, is currently 10th in the line to the throne.

She is set to move up several places to become fourth in the line of succession, behind the Prince of Wales and his two sons.

The Duke of York, Prince Andrew, who is currently fourth, will then drop to eighth.

Some feminists are calling these planned changes a positive sign of progress, in an institution that is often perceived as being discordant with modern times.

Catholics

However it is not just gender that will be affected.

Members of the royal family, who marry a Roman Catholic, will no longer be barred from succeeding to the crown.

However, Catholics themselves will still be barred from the throne.

That’s because of the position of the monarch as the supreme governor of the Church of England.

Yet, the planned reforms to the Royal family are still being widely welcomed.

Some MPs are even suggesting that the future female heir to the throne should also be given the title Princess of Wales.

The changes will also bring us in line with several other modern monarchies.

What other countries have broken with the past

Sweden was first to allow equal succession in 1980, then the Netherlands in 1983, Belgium in 1981, and Denmark in 2009.

Spain is also considering ending male primogeniture.

However, Morocco, Saudi Arabia, Jordan, Oman, Kuwait, Qatar, and Bahrain, do not allow women to take the throne under any circumstances.

Looking to the future

Yet in Britain, for some, it is inconceivable that these changes have taken so long to come about.

Many in the media have highlighted the irony, that the three most successful, and longest reigning, monarchs to have ascended to the English and then British throne have all been women.

Elizabeth I, Queen Victoria and our current Queen Elizabeth II.

Who knows, maybe the royal baby will join their ranks one day.

Either way, if Parliament can secure a breakthrough to make girls and boys equal in the line of succession, the reforms will welcome the crown into the modern age.

Royal baby mania - picture gallery