She said: “This decision and this whole thing was 50 percent William.
“Diana is his mother too. He makes a point about that regularly behind closed doors.
“This was not the right time to bring Meghan in because there is so much tension between Wiliam and Meghan particularly.”
Richard Eden, the Mail’s diary editor, added that the official line from the Sussexes was that “they have a very young baby and it’s just not practical for them to be flying over as a family”.
He said: “It’s not a surprise because she wasn’t expected to attend.
“The day was always very much about Diana and her sons. They are the ones making the speeches.
“Can you imagine Meghan coming over after everything that has passed?”
ITV Royal Producer Lizzie Robinson tweeted: “Meghan will not fly to the UK to join Harry for the unveiling of a statue of his late mother Princess Diana on July 1st, a source confirmed after a US website claimed she would be attending.”
Prince Harry and Prince William will reunite to unveil the statue for only the second time they have met face-to-face since Megxit took place.
The statue is set to be placed and unveiled in the princess’ favourite spot on Kensington Palace’s grounds, in the Sunken Gardens.
The Queen is understood to have invited Prince Harry for lunch at Windsor Castle during his visit amid royal transatlantic tensions.