Prince George still doesn't know he is third in line to the throne

Prince George celebrated his fifth birthday this year but his parents are keeping a very big secret from their eldest son...

Prince George turned five in July and to mark the occasion Kate and William released another adorable portrait.

Taken by the same photographer that captured the nearly-not-released pic from Prince Louis' christening, Prince George is stood in front of a wall with a huge grin on his face.

The little royal looks much more relaxed in front of the lens of Matt Porteous's camera compared to when he is out and about for official engagements – you can literally see the joy in his eyes.

Although Kensington Palace have kept details of Prince George's birthday party under wraps, it is thought the Cambridges were holidaying in the Caribbean.

Kate and William have always stressed that they want to give their children as normal a childhood as possible and they release set portraits simply to satisfy the public interest in their children.

In order to give Prince George, Princess Charlotte and Prince Louis the chance at a normal childhood, the Duke and Duchess of Cambridge are keeping some big secrets from their children.

Including the fact that Prince George is third in line to the throne and will one day replace his Gan Gan (that's the adorable nickname the royals have for the Queen).

The Mirror report that William has always stressed that he is pretty normal behind closed doors and that there is 'a time and a place' for Prince George to be told, it's just not that time yet.

It's possible that William has made this call based on how he found growing up with the weight of the throne on his shoulders.

Catherine Mayer, author of the book Charles: The Heart of a King, has previously said that Prince William struggled with the magnitude of his future role when he was growing up.

In an interview with E! News in 2015 she said: 'With George they are trying to delay that moment of realisation and give him normality before they thrust this on him.

'But it will be, nevertheless, part of his upbringing both in terms of what he sees his parents and grandparents doing and probably quite soon a beginning of an understanding that he is in public life and what that means.'

It's likely that Kate and William have also decided not to tell their children about their impressive net worths. It has been reported that Princess Charlotte's net worth is in the billions and it's much more than her brothers.

So it is probably best not to tell the kids for a while, otherwise a whole new dimension of sibling rivalry could break out and any attempt to keep them grounded might prove unsuccessful...