It is believed one of the reasons the Duchess chose to stay away was that the date of the ceremony also falls on their sin Prince Archie’s fourth birthday.
However Mr Kay claimed it would have been better for all parties if she had decided to travel to Westminster Abbey on May 6.
He said: “It feels like a compromise – Meghan staying away – I think she may come to regret that in the years to come, you don’t get very many coronations and to have a ringside seat at one is seems pretty foolish that she shouldn’t have accepted and come over.
“I think it is the wrong call. I think it would have been better for her and for the Royal Family if they’d both been there.”
He added that Harry’s presence will not end the rift between the families but is instead more of a “ceasefire”.
He explained: “If they can put their differences aside for Harry to come, then it does possibly show that there is a path for the future.”
But he was quick to point out that this was not a “truce” for the two sides.
READ MORE: Harry had ‘tiff’ with royal aide over ‘story’ of Archie’s birth
The Daily Mail’s Diary Editor Richard Eden noted that by agreeing to attend the Coronation Harry has essentially “given in” to his battle to get his family to apologise to him and Meghan.
He pointed to comments made by Harry during his promotional interviews for his autobiography Spare, in which he said that discussions would have to be had between him and his family before making a decision on the Coronation.
However it is believed that no such conversations have ever taken place.
It was announced on Wednesday that after some negotiating Harry would attend the Coronation, nine days after the original deadline to RSVP to invites had passed.
It is thought he will only be making a very brief visit to the UK, just attending the service at the Abbey and not taking part in the procession afterwards or appearing on the Buckingham Palace balcony.
There have also been concerns at the reception Harry and Meghan would receive, with the Coronation marking the first time Harry has been reunited with his family since the publication of Spare.
Despite his attacks on his family in the book, Harry understood his presence at the ceremony would be important on the most significant day of his father’s life.
However both King Charles and Prince William are said to be hurt by Harry’s claims and will not pander to his behaviour.
