The body language expert added: “Harry had always been so gregarious, friendly and extrovert and what looked like this sudden change of mood was quite startling.
“It was like watching Ant and Dec turn up at the same gig but keeping their distance and avoiding eye contact!”
However, there were “ties of friendship” between Harry and Kate.
As the Duke of Sussex leaned across Zara Tindall calling to her husband Mike, Kate can be seen smiling.
Ms James commented: “This is repeated but there seems to be no moment here when the once-so-close brothers even acknowledge one another.”
The rift has since shown no sign of healing, as Harry confided to Oprah Winfrey during his infamous interview on March 8.
Harry told the media mogul that their relationship was still one of “space at the moment.”
In an interview with OK! Magazine, royal author Duncan Larcombe said Prince William had been deeply affected by the fall out.