Prince Harry and Meghan Markle will mark the second birthday of their son, Archie, who helped inspire his mother’s new picture book.

The Duke and Duchess of Sussex's first child has spent much of his life living in north America with his parents.

Archie Harrison Mountbatten-Windsor was born on May 6 2019 at 5.26am, weighing 7lb 3oz, and a few days after his birth his parents proudly showed him to the world, before the Queen and Duke of Edinburgh saw him for the first time.

The little boy has only been seen rarely during the past 12 months, but did feature in a black and white video clip released in March, showing him walking along a beach watched by his parents and the family’s pet dog, Guy.

As he walked towards his father, who filmed the moment, the youngster ducked down and walked through the gap in his legs.

When he made a surprise appearance in the Sussexes’ first podcast for Spotify in December, his American accent could clearly be heard as he was encouraged to say a few words for the audience.

In an interview with Oprah Winfrey earlier this year, Meghan Markle suggested she and Harry wanted Archie to be a prince so he would have security and be protected.

The duchess expressed her shock at “the idea of our son not being safe”, and the idea of the first member of colour in this family, not being titled in the same way as other grandchildren.

Dorset Echo: Duke and Duchess of Sussex during their interview with Oprah Winfrey. (Harpo Productions/PA)Duke and Duchess of Sussex during their interview with Oprah Winfrey. (Harpo Productions/PA)

But Archie, who is seventh in line to the throne, is not entitled to be an HRH or a prince due to rules set out more than 100 years ago by King George V.

Meghan expressed concern over the idea of her family “not being safe” claiming the decision not to make Archie Mountbatten Windsor a prince goes against convention.

The Duchess of Sussex shared her thoughts on the "idea of the first member of colour in this family, not being titled in the same way that other grandchildren would be".

She said: “It’s not right to take it away.”

Should Archie be a prince?

The decision to not make Archie a prince relates to rules set out by King George V over 100 years ago.

While the Queen remains on the throne, Archie is too far removed from the throne to be a prince due to the size of the Queen’s extended family and long reign.

According to a Letters Patent issued by Harry’s great-great-grandfather in 1917, Archie would be entitled to be named a prince when Prince Charles sits on the throne and Archie becomes a direct grandchild of the monarch.

It is not yet clear if this will be the case when the Prince of Wales sits on the throne.

King George V’s patent read: "...the grandchildren of the sons of any such sovereign in the direct male line (save only the eldest living son of the eldest son of the Prince of Wales) shall have and enjoy in all occasions the style and title enjoyed by the children of dukes of these our realms."

According to this rule, only Prince George, great-grandson of the monarch and in the direct line of succession to the throne, is entitled to be a prince.

The line of succession can be seen in the image below.

Dorset Echo: Royal family tree. (PA Graphics)Royal family tree. (PA Graphics)

However, the Queen issued a Letters Patent ahead of Prince George’s birth to ensure all of the children of Prince William and Kate Middleton would hold such titles.

Had it not been for the Queen, Princess Charlotte and Prince Louis would not have been HRHs and would have been titled Lady and Lord.

The key difference is that children of the Duke and Duchess of Cambridge are children of the future monarch whereas Archie will not.

What title will Archie hold?

Dorset Echo: Duchess of Sussex with their baby son Archie Mountbatten-Windsor in 2019. (PA)Duchess of Sussex with their baby son Archie Mountbatten-Windsor in 2019. (PA)

As first son of the Duke and Duchess of Sussex, Archie will eventually be entitled to take over his father’s title of the Duke of Sussex.

As first born of Harry, a Duke, Archi could have become Earl of Dumbarton, one of Harry’s other titles or Lord Archie.

However, Harry has stressed his eagerness to give his sone the opportunity of an ordinary life, away from the Royal Family, an opportunity he never had.

When Archie was born, a royal source said that Prince Harry and Meghan had decided to give their son the regular title of Master Archie Mountbatten-Windsor.

Meghan opposed this in her interview with Oprah saying: "It was not our decision to make."

When asked if Archie being a prince was important to her, Meghan replied: "If it meant he was going to be safe then of course."