Prince Harry and Meghan Markle receive subtle message as duchess discusses Princess Kate's health

The royal was also asked for an update regarding the Princess of Wales and King Charles.

Buckingham Palace announced that King Charles had been diagnosed with a form of cancer in February.

The monarch returned to public-facing duties in late April with an engagement at the Macmillan Cancer Centre in London and discussed the treatment he was receiving.

In March, the Princess of Wales announced that cancer was found in tests following a significant abdominal surgery earlier this year.

Princess Kate released a video message confirming the diagnosis and revealing she had undergone preventative chemotherapy.

The Princess of Wales has not returned to public duties as she continues to focus on her health following the diagnosis.

Sarah Ferguson said regarding Kate and the King: "The great example they have set is that they have spoken about it themselves.

"Princess Catherine was so brave and courageous.

"[Kate is] such a wonderful mother and an inspiration to all of us."

The Duchess of York also stressed the importance of family unity amid the ongoing feud between senior royals and Prince Harry and Meghan Markle.

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Ferguson said: "Family unity is key, we should all unite in order to really feel better."

The Duke and Duchess of Sussex have not been invited to the Trooping the Colour event on June 15 for the second year in a row.

The couple will also miss the Duke of Westminster's wedding on Friday, June 7 despite Hugh Grosvenor being their son's godfather.

Harry and Meghan declined an invite to the wedding to avoid an awkward reunion with Prince William, who will be an usher at the event.