In their senior positions, Kate and Sophie will usually attend Royal Family events such as Trooping the Colour and the Remembrance Day Cenotaph service.
When they are spotted together, body language expert Judi James suggested Kate and Sophie get on well.
She explained both royals appear to enjoy each other’s company.
Sophie also seemed to look out for the Duchess of Cambridge, Judi suggested.
She told Express.co.uk: “Many of the poses of the two women together show Sophie face-checking Kate with quite strong bouts of watchful-looking eye contact to suggest she’s taking a semi-maternal approach.
“She also has raised brows and what’s called a ‘pinging’ smile that implies she wants to ensure Kate is enjoying herself.
“There is some mirroring when the two women walk together but it’s primarily Sophie projecting the stronger signals of relaxed confidence while Kate smiles happily at her side.”
Sophie and Kate’s close bond could have been helped by Sophie’s attitude to her royal role.
Judi added: “This attitude must have made her the perfect royal wife to welcome and induct Kate into the Royal Family.
“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.”
When trying to adapt to her royal role, Kate may have looked to Sophie for advice.
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The royal line of succession – who outranks who?
The line of succession to the British throne dictates the order in which each member of the Royal Family would ascend to the throne.
It is also seen as a ranking of importance with the head of the line, the Queen, taking the place of ruler.
Older children come before younger children. Traditionally boys came before girls, but this law was changed on 26 March 2015 before the birth of Prince William’s first child.
Incredibly, Catholics are still excluded from the line of succession, as are children born outside of wedlock.
The royals, who usually stick to a strict protocol when appearing in public, often arrive at events in ascending order of importance, with the most important royal arriving last.
Prince Charles, 71, is currently second-in-line to the British throne, followed by Prince William, 38, his oldest son.
Then comes Prince William’s children, George, seven, Charlotte, five, and Louis, two, and they are followed by Prince Harry, 35. Prince Harry is succeeded by his son Archie Harrison, born in May 2019.
— to www.express.co.uk