It may feel weird when we hear our national anthem change to "God save the King" during country-wide events and sporting competitions.
But when it does change, it will stay that way for a long time, as the next three successors are male.
Prince Charles is the next in line to become head of the Royal family and in doing so will become the oldest ever UK-Monarch to be crowned.
Following on from his father will be the Duke of Cambridge, Prince William.
Although it may seem a long way off, Prince George could become King one day too.
But at what age will Prince George become King, and what happens if he turns it down?
When will Prince Georg e become king?
Prince George will assume all royal duties when the crown is passed down from his father Prince William, Duke of Cambridge.
When he does become king it is likely he will be crowned King George VII.
How old does Prince George have to be to become King?
Prince George can become King at any age. However, if he has to be anointed before he is 18 years-old a regency is automatically established.
According to the standing Regency Acts, if the Monarch is under the age of 18 royal roles and functions are taken on by an appointed regent.
This continues until the King or Queen-to-be is old enough to absorb their powers, as traditional as they may be.
So despite having the title, no responsibility would be placed on future King George until his 18th birthday.
What would happen if Prince George decided not take the crown?
If Prince George decided to withdraw himself from royal responsibilities then he could do so. This is known as an abdication.
In this case the crown would pass to his eldest sibling, Princess Charlotte.
Princess Charlotte is currently fourth in line to the throne, ahead of her younger brother Prince Louis.
Queen Elizabeth's rule title rule change
When Queen Elizabeth had her children, her royal daughter Princess Anne was demoted in line the throne, losing out to younger brothers.
This was because throughout history male members of the royal family were automatically promoted in succession rankings.
But thanks to the 2013 Succession to the Crown Act, introduced by Queen Elizabeth, the rules changed to allow for female royals to hold the same right to the throne as their brothers.
We saw it take effect when the Duke And Duchess's youngest Prince Louis arrived in 2018, and Charlotte maintained her place as fourth in line to the throne.
