KING Charles has made a "significant step" in his cancer treatment following his Easter Sunday appearance, a source has revealed.
His Majesty greeted around 60 well-wishers after leading a scaled-down Royal Family to a service at Windsor Castle today.
An insider said: "Today was a significant step.
"As can be seen, The King has responded to treatment very encouragingly over the past weeks and his doctors were thus able to adjust their guidance slightly on what His Majesty is now able to undertake, including attendance at the Easter Service and greeting well-wishers who had kindly turned out to show their support."
The health update comes eight weeks after Buckingham Palace revealed the King, 75, was undergoing treatment for cancer.
His diagnosis followed treatment for an enlarged prostate in January.
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The Palace had said the King would not undertake any official public engagements while he undergoes treatment.
He has been carrying out all official duties in private.
Towards the end of February, Charles had an audience with Prime Minister Rishi Sunak and held a Privy Council in his first face-to-face official duties since the diagnosis.
Earlier in March, the King held an in-person pre-Budget audience with Chancellor Jeremy Hunt, had a video call with Canadian prime minister Justin Trudeau, and had an audience with Baroness Scotland.
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Over the course of the month, he also welcomed a series of foreign officials to Buckingham Palace, including high commissioners of Jamaica, Tanzania and Singapore.
The King has responded to treatment very encouragingly over the past weeks and his doctors were thus able to adjust their guidance slightly on what His Majesty is now able to undertake
Source on King Charles's condition
Ahead of Easter, the King reaffirmed his coronation pledge "not to be served, but to serve" with "my whole heart" in an audio address broadcast to a congregation at Worcester Cathedral where the Royal Maundy Service was held in his absence on Thursday.
But because he has responded "very encouragingly" to treatment, doctors have "slightly" adjusted their guidance on what commitments Charles can undertake, it is said.
A source said: "To be clear, His Majesty's treatment continues and caution is of course the watchword.
Why Charles bravely shared his cancer diagnosis
KING Charles bravely broke with royal protocol by sharing his cancer diagnosis.
Senior royals have in past been tight-lipped about their health battles.
The last top royal diagnosed with cancer was Charles's grandfather George VI.
Heavy smoker George had his left lung removed for "structural abnormalities" in September 1951, months before he died.
The "abnormalities" were actually a life-threatening carcinoma, but the public never learned about George's cancer ordeal.
Buckingham Palace said Charles wanted to share his cancer diagnosis to boost "public understanding" for cancer patients worldwide.
"But as diary plans are evolved towards summer, we hope to see more of these carefully-calibrated steps towards the resumption of some public facing duties for The King, with adjustments made where necessary.
"Nothing will be confirmed until nearer the time, plans remain in flux and are subject to medical guidance, but there is great hope and optimism from both doctors and the patient.
"While His Majesty has of course been undertaking all his official duties in private, and has been photographed at a number of smaller Palace engagements.
"Hopefully today has offered wider public reassurance that His Majesty is doing well and that the road ahead is looking very positive."
ROYALS IN ATTENDANCE
The King was today accompanied by Queen Camilla for the annual Easter Mattins Service.
The Prince, Princess of Wales and their three children were not in attendance.
Kate, 42, is currently undergoing "preventative" chemotherapy for cancer.
Prince Edward, Duke of Edinburgh, Sophie, Duchess of Edinburgh and James, Earl of Wessex, were also in attendance at St George's Chapel.
The King's disgraced younger brother Prince Andrew, 64, arrived by car with Princess Anne, 73, and her husband Vice Admiral Sir Tim Laurence, 69.
He was joined by ex-wife Sarah Ferguson, 64, who herself has had breast cancer and skin cancer in the past nine months.
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It was Fergie's first appearance at Easter Mattins service since she divorced Andy 28 years ago.