Prince Archie and Princess Lilibet are 'not known' by George, Charlotte and Louis

The Wales family are now said to have "replaced" the cousins with Zara and Mike Tindall’s three children, Mia, Lena, and Lucas.

Dampier added it is unlikely that the relationship between the Wales and Sussex cousins will develop in the next couple of years.

The royal author told The Sun: "It’s so sad that the Wales’ kids basically know very little about their cousins across the pond and are never likely to be close to them. It’s not thought that George Charlotte and Louis have ever met Archie and Lilibet.

“Although they were invited to Lilibet’s first birthday party at Frogmore Cottage, they did not go.

"In many ways the children of Zara and Mike Tindall have replaced Archie and Lilibet as the closest cousins of George, Charlotte and Louis. Their children Mia, Lena and Lucas are similar in age and when they see each other the fun is infectious.

“At Christmas at Sandringham, at events like Trooping the Colour, state occasions or holidays at Balmoral, the cousins play together and get on well. It’s something Archie and Lilibet are missing out on and you just wonder if in years to come, when they grow up, they will start asking their parents why they are estranged from the Royal Family."

LATEST ROYAL NEWS

• King 'not planning to visit areas impacted by riots' amid chaos
• Zara Tindall breaks silence on her 'hopes and dreams' after suffering heartbreak
• Meghan's new lifestyle brand suffers huge new setback over 'irregularities'

The royal expert said it is unlikely that the relationship between the Wales and Sussex cousins will develop in the next couple of years.

Dampier added: "I’m sure William and Kate think it’s tragic that it’s come to this but the rift between William and Harry is so bad that I don’t see any resolution soon, if ever.

"Harry has said in a recent interview that he won’t bring Meghan back to the UK, and I’m sure he wouldn’t bring their kids without her, so it’s a non-starter.

"There is no way William and Catherine are going to travel to the US to see the Duke and Duchess of Sussex, so it’s a stalemate.”

Dampier also added how beneficial Zara is to the family as an 'asset' and could be key to healing relationships between the two brothers.

He said: "If anyone is going to bring William and Harry together it could well be Zara who acts as the peacemaker. In fact Zara is a tremendous asset to the family generally as she gets on well with everyone and is a calming influence.

"Zara brings people together and whenever you see her with other members of the family she is always very warm and loving, the first to hand out hugs and kisses."