They've been married for 11 years, and in that time Prince William and Kate Middleton have rarely been seen indulging in public displays of affection.
Unlike Meghan Markle and Prince Harry, who openly hold hands wherever they go, Kate and William prefer to keep a distance, limiting contact to an occasional - and brief- hand on the back.
Instead, the couple - who made a joint appearance at Wimbledon today - are famed for exchanging cheeky grins and subtle looks at public events.
And according to body language expert Darren Stanton, the pair eschew PDA because their 'deep' bond means they don't have anything to prove.
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“She and William are a pair that appear so connected on a deeper level that they don’t need to be showing continuous signs of reciprocal liking - like tactileness or prolonged eye contact - during public outings to prove they have a deep connection," Darren told The Mirror, speaking on behalf of Slingo.
"It is noticeably visible without the need for the couple to indulge in overzealous PDAs and is testament to why Kate and William have the confidence to attend events as individuals as much as they do as a couple."
Referencing their outing today, he continued: "For instance, Kate, walking across the bridge as she arrived to the grounds, displayed the same level of confidence solo as she did when sat alongside William in the stands."
Furthermore, Darren says it's clear to see that after years of engagements, Kate and Wills have learned how to operate as separate parts of the same unit without needing to exchange a word.
“It’s interesting, as the couple were in complete unison with their behaviour while spectating," he added.
"During a tense moment on court, Kate was seen anxiously tucking her hair behind her ears as William pulled an expression of tension.
“As always an outing on such a public scale sees Kate and William setting the scene and a precedent for how things are to be for when William becomes King.
"They are two individuals who aren’t afraid to be themselves while still upholding their Royal duties graciously and as best they possibly can.”
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