Diana, Princess Of Wales is most commonly referred to as Princess Diana – but this is not strictly correct.
While she may have been the Peoples Princess, Prince William and Prince Harrys mother was never officially a Princess.
Similarly, while Kate Middleton might have been referred to as a Princess on Prince Louis birth certificate when she gave birth in April, strictly speaking she is not either.
So why is this?
When Kate married Prince William on 29 April 2011, she still adopted a fancy title – Her Royal Highness The Duchess Of Cambridge – or Catherine, Duchess Of Cambridge. But she was never Princess Kate.
Dianas official title upon marrying Prince Charles Of Wales on July 29 1981 was Her Royal Highness The Princess Of Wales. She was also known as Diana, Princess Of Wales.
And while Diana – who was formerly known as Lady Diana Frances Spencer – may have had Princess within her full name, it was never her formal title, which would require Princess coming first, followed by her first name, much like Princess Charlotte.
In fact, Diana herself admitted that her public-given title of Princess Diana was not formally correct.
Prince William was born His Royal Highness Prince William Of Wales – and is referred to as Prince William as he was born into the Royal Family – the Queen gifted him a new title on his wedding day, becoming the Duke Of Cambridge.
This is why Kate – whose full name is actually Her Royal Highness The Duchess Of Cambridge, Countess Of Strathearn and Lady Carrickfergus – became a Duchess instead of having Princess within her title like Diana did.
Similarly, Harry became the Duke of Sussex when he married on 19 May this year, making Meghan a Duchess rather than having Princess in her name.
So while Diana indirectly became a Princess upon marriage, she was not an official Princess as for someone to assume the title of Princess, they must be born into the Royal Family, just like Princess Charlotte is a Princess because of her fathers status.
However, if Harry and Meghan were to have children, they would not automatically be called Prince or Princess as theres another layer to the Princess rule.
Meghan and Harrys children would be given the title of Lord or Lady, taking the surname Mountbatten-Windsor – a nod to Prince Philips family name.
In 1960, the Queen passed a ruling which only entitled the children or the grandchildren of the sovereign to take the title of Prince or Princess.
However, for the grandchildren to take the titles, they must be born to the sovereigns son – not daughter.
In the case of Zara and Peter Phillips, for example, they are the children of Princess Anne. Anne is the Queens daughter and as the children of the monarchs daughter, they do not hold a royal title.
All of their cousins are children of the monarchs sons – Charles, Edward and Andrew – so their children do get the royal titles, such as Prince William, Prince Harry, Princess Beatrice and Princess Eugenie.
So why are Prince George, Princess Charlotte and Prince Louis allowed to carry the coveted titles?
In 2012 – one year after Kate and William married – the Queen allowed all children of William and Kate – her and Prince Philips great-grandchildren – to take the Prince or Princess titles too.
And thats why George, Charlotte and Louis are fully-fledged Princes and Princess.
However, if Princess Charlotte has children, they will still not be able to take the Prince or Princess title, just Princess Annes children were not.
The Queen may also choose to make an exception for Harrys children, if he and Meghan choose to start a family, like she did for William.
But Harry and Meghans prospective children could be upgraded to Prince or Princesses when the line of succession to the throne changes as Prince Charles ascends the throne.
What is the current line of succession to the British throne?
The following line of succession accounts for Mike and Zara Tindall's second child, due this summer.
Reigning monarch: Queen Elizabeth II (born 1926)
1st – Charles, Prince of Wales (b. 1948)
2nd – Prince William, Duke of Cambridge (b. 1982)
3rd – Prince George of Cambridge (b. 2013)
4th – Princess Charlotte of Cambridge (b. 2015)
5th – Prince Louis of Cambridge (b. 23 April 2018)
6th – Prince Henry of Wales (Prince Harry) (b. 1984)
7th – Prince Andrew, Duke of York (b. 1960)
8th – Princess Beatrice of York (b. 1988)
9th – Princess Eugenie of York (b. 1990)
10th – Prince Edward, Earl of Wessex (b. 1964)
12th – James, Viscount Severn (b. 2007) B D W
12th – Lady Louise Windsor (b. 2003)
13th – Anne, Princess Royal (b. 1950)
14th – Peter Phillips (b. 1977)
15th – Savannah Phillips (b. 2010)
16th – Isla Phillips (b. 2012)
17th – Zara Tindall (née Phillips; b. 1981)
18th – Mia Tindall (b. 2014)
19th – Baby girl Tindall (b. 18 June 2018)
20th – David Armstrong-Jones, 2nd Earl of Snowdon (b. 1961)
Prince Harry would then likely become HRH The Prince Henry, meaning Meghan would become HRH The Princess Henry.