Prince William steadfastly refused to make eye contact with his younger brother Prince Harry during the Queen's Thanksgiving Service.
There was no obvious interaction shown on the camera between Harry and his brother William, who have long faced a rift, and they sat apart during the service at St Paul's Cathedral on Thursday.
The Duke and Duchess of Sussex returned to the royal fold for the celebrations but sat in the second row, behind the Countess of Wessex and the Duke and Duchess of Gloucester.
They were across the aisle from Prince Charles, the Duchess of Cornwall and the Duke and Duchess of Cambridge,
Working royals filled the front-row chairs, meaning there was no place there for Harry and Meghan Markle.
Speaking to the Australian morning programme Sunrise, Mirror Royal Editor Russell Myers said: "It was very, very frosty inside the church.
"You could cut the atmosphere with a knife.
"The brothers didn't lock eyes or make eye contact at all. Harry was craning his neck to look at William and William didn't look back at him.
"I think there's still a lot of bad atmosphere going on and there needs to be a bit more water under the bridge until those brothers come back together."
The Duke and Duchess of Sussex returned to the royal fold for the Queen’s Jubilee celebrations – but their relegated seats were a telling sign of their change in status.
It was their first public appearance alongside the Windsors since they stepped down as senior royals two years ago amid the Megxit storm.
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Meghan, in an elegant Dior trench coat and matching hat, smiled as she walked through the church, while Harry bit his lip at times, while also nodding greetings to members of the congregation.
Just over a year ago, Harry and Meghan accused an unnamed member of the royal family, not the Queen nor the Duke of Edinburgh, of racism and painted the monarchy as an uncaring institution in their controversial Oprah interview.
Speaking on Friday, royal expert Omid Scobie said Harry and Meghan hope to be as "low-profile as possible" during their trip to the UK for The Platinum Jubilee.
Mr Scobie added: "I spoke with people close to the couple... who said that they want to be as low-profile as possible during this trip.
"It's almost hard to believe, but I think yesterday Trooping the Colour was a great example. We didn't really catch sight of them on TV cameras."
Kate was publicly singled out by Meghan for allegedly making her cry in the run-up to her wedding.
The mass gathering of nearly 50 royals including Harry and Meghan was invited to a special celebratory reception at the Guildhall afterwards.
But the Sussexes chose not to attend, and are thought to have returned to their Frogmore Cottage base, where they will be celebrating daughter Lilibet's one-year birthday today.
The Queen was missing from the gathering but the Duchess of Cambridge said later she had enjoyed Thursday’s historic Platinum Jubilee celebrations but the day had been “very tiring”.
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