KING Charles is “frustrated” that his recovery from cancer treatment is taking longer than “he would want it to", Peter Phillips has revealed.
The son of the Princess Anne said the monarch was “in good spirits”, but was “pushing” his staff to be able to return to his duties after beginning "pioneering" treatment last month.
Mr Phillips, whose sister Zara is a former Olympian equestrian, told Sky News Australia: "I think ultimately he's hugely frustrated.
"He's frustrated that he can't get on and do everything that he wants to be able to do.
"But he is very pragmatic, he understands that there's a period of time that he really needs to focus on himself.
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"But at the same time he is always pushing his staff and everybody - his doctors and nurses - to be able to say 'actually can I do this, can I do that?'"
Charles has been receiving treatment for an undisclosed form of cancer since early February after he was treated for an enlarged prostate.
The Palace has not confirmed the type of cancer, but it is understood not to be the prostate.
It comes after bombshell news on Friday that the Princess of Wales was undergoing preventative chemotherapy for cancer.
Peter added: "I think the overriding message would be that he's obviously very keen to get back to a form of normality and is probably frustrated that recovery is taking a little longer than probably he would want it to."
The son of Anne and her first husband Captain Mark Phillips, said during the interview on Australian television that his mother "leaves others to worry about column inches".
Peter said: "I think in the past she has not always been the media's favourite so to speak. But she's never really let that bother her.
"She just keeps her head down the whole time and keeps working away and leaves others to worry about column inches."
The eldest grandchild of Queen Elizabeth II added that it was "pretty remarkable" that his mother was still carrying out overseas trips in her 70s.
Meanwhile, Peter said the "work ethic" of his parents had been hugely influential for him and his sister Zara Tindall.
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He is currently visiting Australia as a patron of the charity ISPS Handa.
The Princess of Wales, 42, revealed her health battle to the world in a touching video in which she vowed she was “going to be OK”.
And it was revealed that Kate met the King on Thursday for a heart-to-heart at Windsor Castle, where it is understood she told him about her speech.
Charles has rallied around his "beloved" daughter-in-law during her ordeal as someone who can understand what she's going through.
After Kate’s cancer statement, Buckingham Palace said: “His Majesty is so proud of Catherine for her courage in speaking as she did.
“Following their time in hospital together, His Majesty has remained in the closest contact with his beloved daughter-in-law throughout the past weeks.
It is understood Charles had been made aware of Kate’s cancer struggle before he travelled from London for the lunch.
Doting husband Prince William has been by her side throughout - taking a step back from his royal duties and pulling out of engagements last minute.
Queen Camilla is also said to be a pillar of support and in regular contact with Kate.
Camilla has been Charles' "rock" following his diagnosis and wants to be as supportive for Kate.
KING'S REST
The King has spent most of his weekdays at Windsor Castle but has regularly gone to London to carry out official royal duties at Buckingham Palace.
He left Windsor Castle at 11am on Friday to rest for the weekend at his Highgrove House residence in Gloucestershire.
The Queen has been filling in at major engagements including a visit to Northern Ireland last week.
While there she told well-wishers her husband is “doing very well” and “very disappointed he couldn’t come”, for what was originally intended to be a joint visit.
Meanwhile Kate has been recuperating at Adelaide Cottage, Windsor, with William, 41, and their children.
They will not attend the family Easter Sunday service which is expected to be held at St George’s Chapel at Windsor Castle.
However, it is understood the King is hoping to lead the family to the ceremony at Easter.
The Queen, 76, is also hoping to join her husband for the service which is expected to be a scaled-down affair with only a handful of royals attending.
She stood in for Charles and William at a service of thanksgiving for the life of King Constantine II of Greece at the chapel in February.
Kate and William have now pleaded for privacy as they spend time together during their children’s school holidays.
Kate’s statement on Friday was issued to coincide with all three children finishing school term.
They are due back at Lambrook School, Berkshire, on April 17 and William will not return to work until then.
