“I’d like to think that at some point the penny has dropped with Harry and he realises that he has permanently damaged his relationship with his blood family, but I wouldn’t bet on it.

“It’s very sad because Harry was once so popular and the King is not seeing his grandchildren.”

The Duke and Duchess of Sussex were noticeably absent from this year’s Trooping the Colour earlier this month – with the couple facing a snub for the second year in a row as they did not receive an invite to the event.

Despite her cancer battle, Princess Kate – who revealed her diagnosis back in March – made her first appearance of the year alongside her three children.

Although it remained unclear whether she would be able to attend, Kate’s appearance was confirmed the previous day – on June 14 – via a statement, which also contained an update on her health.

She wrote: “I am making good progress, but as anyone going through chemotherapy will know, there are good days and bad days. “On those bad days, you feel weak, tired and you have to give in to your body resting. But on the good days, when you feel stronger, you want to make the most of feeling well. My treatment is ongoing and will be for a few more months.”

The statement continued: “I’m looking forward to attending The King’s Birthday Parade this weekend [June 15] with my family and hope to join a few public engagements over the summer, but equally knowing I am not out of the woods yet.

“I am learning how to be patient, especially with uncertainty. Taking each day as it comes, listening to my body, and allowing myself to take this much-needed time to heal.”