Sophie married Prince Edward in 1999 and Camilla joined the family six years later at her wedding with Prince Charles.
Both women were given royal titles on their big day and took on working roles within the family.
These roles have seen them step out together at lots of royal events such as Trooping the Colour and royal Remembrance services.
Despite many meetings, and although they have known each other for more than 15 years, they may not have the closest relationship.
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That’s according to Judi James who has commented on some of their interactions with each.
She suggested it may be surprising, but the royals do not show signs of being particularly close.
Judi said: “It’s difficult to imagine the very sociable and approachable Sophie Wessex not getting on with any other members of the family.
“But the body language in these shots of her attending events with Camilla does suggest an air of coolness could exist between the two women.”
The expert claimed Sophie is usually “chatty” while Camilla can sometimes appear “nervous”.
The contrast in personalities should work as Sophie would be the perfect candidate to comfort her sister-in-law.
However, Judi continued to say this has not obviously been the case during their various public meetings.
She continued: “Sophie tends to be very chatty and relaxed at royal events, which should suit the rather nervous-looking Camilla perfectly.
“But there is no evidence here that Sophie is going out of her way to support or reassure her sister-in-law or put her at her ease.”
The expert highlighted this is particularly unusual as Sophie has shown close bonds with other royals.
Judi added: “The fact that she is sending out so many signals of rapport and friendship to other royals like Kate tends to make the lack of them with Camilla even more obvious.”
Sophie took to her royal role naturally and seems to have adapted well to life in the public eye.
The Countess of Wessex is thought to have a close relationship with royals including Kate Middleton and Queen Elizabeth II.
Kate, Duchess of Cambridge, joined the Royal Family more than 10 years after Sophie.
As the young royal took on a senior role, Sophie appeared to be the one on hand to offer guidance when needed.
Judi said: “Sophie’s attitude must have made her the perfect royal wife to welcome and induct Kate into the Royal Family, especially in the face of William’s horror of bringing Kate into the same circus that he watched his mother suffer.
“Sophie’s formula does appear to have been copied by Kate too as – so far – she has managed to tread the very fine line of creating interest that is positive but not unmanageable.”