Kate and William have an 'industrial-strength' relationship... because they greet crowds in the same way

Kate and William have an 'industrial-strength' relationship... because they greet crowds in the same way - Kate Middleton and Prince William are not very big on public displays of affection - and many would say that is the way it should be for a future King and Queen.

But their closeness has apparently still been on display every time they greet their supporters... through their identical royal waves.

Photos taken during the pair's visits to Wales, Scotland and Northern Ireland have shown the couple are so in tune they greeted crowds in the same way.

Synchronised windscreen-wiper wave: William and Kate both wave in an identical way with their left palms facing those they are greeting

William's mother, Diana, Princess of Wales, had the ability to make people feel they were singled out with a wave. Her son has inherited this trait and passed it on to his fiancee.

Body language expert Judi James, who has written books on behaviour, communication and body language, studied recent images of William and Kate.

She observed that the Prince and his fiancee both use their left hands to greet the crowds with their palms facing the well-wishers.

Ms James said: 'Like-bodied" suggests "like-minded" and this strongly mirrored wave shows industrial-strength levels of rapport.

'The open palm display signals openness and approachability that is only slightly tempered by the fact that it is very similar to the signal for "Stop".'

One picture taken when they returned to St Andrews Universty in Scotland last month, where the pair met as students and shared a house, showed Kate with a similar wave to her fiance, despite having her back to him.

Like-bodied: The pair even wave in the same way when they are not facing each other

Ambidextrous: Although the pair usually wave with their left hands, they use the same technique when waving with the right one

When the couple attended their first official engagement together in February in Anglesey, north Wales, their shared gesture, a wave with the hand bent at the wrist, was seen as they walked up some steps.

Ms James added: 'Bending the hand back on the wrist could look hugely dominant, more like a hail than a wave, but with their arms held low it's got a pseudo-infantile look that implies cuteness and fun rather than stuffy formality.

'It's called the windscreen-wiper wave and is often used by A-list celebs who want to promote an image of being normal and down-to-earth.'

Like mother, like son: William inherited his ability to make people feel singled out - and his wave -from Princess Diana

Cuteness and fun: The wave used by Diana is often used by celebrities who want to promote an image of being normal and down-to-earth

Speaking about Diana, the expert said: 'The Princess had a knack of sending body language tie-signs out to the public that made us feel as though we knew her personally, like little eye-rolls, glances or self-effacing smiles as she attended formal occasions.'

The expert explained that a 'personal wave' is 'something that seems intimate, like a conversation with the viewer or the feeling they are signalling to you. William has picked up on the trait and Kate's carrying it off with even more confidence'.

James also examined a picture of the Queen and Duke of Edinburgh waving and another showing the Prince of Wales and Duchess of Cornwall but concluded the Prince and his fiancee seemed the most together.

Royal wave: Charles and Camilla wave in a similar way too

She added: 'They are the most synchronised of the royal couples, which reflects the current stage of their relationship.

'For royals, they have a unique amount of shared experiences, having studied together and lived in the same house.'

The expert described the Queen's wave as 'feminine-formal' and a little 'stilted', while Philip opted for more of a hail than a wave 'something much more active and full of machismo'.

Charles and Camilla's wave was more synchronised and showed 'warmth and friendliness', but like his father, the heir to the throne used his arm right up to and including the shoulder to show his status and masculinity. ( dailymail.co.uk )