King Charles Seen in New Photos at Buckingham Palace Meeting amid Cancer Treatment

The King did not attend the Commonwealth Day Service at Westminster Abbey on Monday, but addressed the crowd via video

King Charles is busy with work behind the scenes while receiving cancer treatment.

On Wednesday afternoon, the King, 75, received Baroness Scotland of Asthal, the Commonwealth Secretary-General, at Buckingham Palace. King Charles was photographed smiling and sharing a handshake with the diplomat during the private meeting.

According to the Court Circular, King Charles also held a council and several audiences, including with British Prime Minister Rishi Sunak, though those meetings were not caught on camera.

Baroness Scotland heads the Commonwealth Secretariat, the main intergovernmental agency of the global network of 56 countries united by the crown, and joined Queen Camilla, Prince William and other members of the royal family at the Commonwealth Day Service at Westminster Abbey on Monday. The King did not attend the event with 2,000 guests as he refrains from public-facing duties, in accordance with the Feb. 5 announcement from Buckingham Palace about his cancer diagnosis.

Related: A Complete Timeline of King Charles' Cancer Diagnosis and Treatment

The monarch still addressed the Commonwealth Day congregation through a pre-recorded video, where he expressed thanks for all the well-wishes about his health and vowed to serve “to the best of my ability.” The service celebrated the 75th anniversary of the Commonwealth — the family of nations mostly linked to the U.K. through the British Empire. Beyond the United Kingdom, Charles is King of 14 of the nations, including Canada, Australia and New Zealand.

There was a hiccup with the release of the remarks, however, as it was accidentally linked to the personal YouTube account of the Palace's Head of Digital Engagement, Emma Goodey. Courtiers quickly fixed the mistake.

Related: Royal Family in Turmoil as Demands Mount for More Transparency: 'There Is Too Much Uncertainty' (Exclusive)

Queen Camilla, 76, has been a steady presence while King Charles has been outside of the public eye and attended the Commonwealth Day reception that Baroness Scotland hosted in London on Monday night.

While King Charles was undertaking meetings at Buckingham Palace on Wednesday, Queen Camilla stepped out at the Cheltenham Festival for a day of horse racing. Other royal family members in attendance at the event included Princess Anne, Princess Eugenie and Zara Tindall.

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A source close to the royal household says the King is "coping well" with his cancer treatment, but there’s still growing concern about his health. The monarch has not disclosed his specific diagnosis, which Buckingham Palace announced following his treatment for benign prostate enlargement in January, though a spokesman confirmed it is not prostate cancer.

"Everybody feels unsettled by uncertainty, and there is too much uncertainty that is surrounding the monarchy right now," royal biographer Sally Bedell Smith tells PEOPLE. "Queen Elizabeth used to say, 'I need to be seen to be believed.' It is important for Charles and his reign for the public to know a little bit more."

Bedell Smith also says, "Even though he has revealed that he has a form of cancer, that has done nothing to quell the speculation about how seriously ill he may or may not be. That is not doing the monarchy any favors. He is the head of state, and there are constitutional implications.”

In addition to King Charles' health issues, Kate Middleton also postponed public duty during her private recovery following abdominal surgery until at least Easter.

Adding to the recent turmoil surrounding the royal family, the Princess of Wales issued a surprise apology on Monday regarding the Mother's Day photo circulated over the weekend after multiple global photo agencies pulled the picture due to suspicion of manipulation.

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