On Tuesday, both the monarch and Queen Camilla - who will mark one year since their coronation on 6 May - appeared to be in great spirits as they visited University College Hospital Macmillan Cancer Centre where they spoke to medical specialists and patients.
In a touching moment, Charles warmly held hands with cancer patients as he took the time to hear their stories. During one conversation, His Majesty confessed it was a "bit of a shock" when he was given his own cancer diagnosis. Asked how he is doing by one patient undergoing chemotherapy, the King replied: "Not too bad. It's always a bit of a shock, isn't it, when they tell you?"
The King was asked how he was feeling, saying: "I'm alright thank you very much, not too bad." He is understood to be having further treatment later on.
This outing marks the first in a number of many external engagements His Majesty will undertake in the weeks ahead after confirming the positive effect of his cancer treatment.
The royal couple are raising awareness of the importance of early diagnosis and are highlighting innovative research, supported by Cancer Research UK.
The big return
King Charles appeared to be in good health as he entered the University College Hospital Macmillan Cancer Centre.
Official duties
The 75-year-old is Patron of Cancer Research UK and Macmillan Cancer Support. The charity provides a wide range of support to people living with cancer and promotes better cancer care.
Always by his side
Queen Camilla accompanied the King on his first official public outing. The royal couple happily waved at well-wishers.
King Charles has been receiving care as an outpatient since early February, and sources have said that despite the welcome news the King still has cancer and will continue to be treated for the undisclosed form of the disease.
Health update
The King reassured fellow cancer patients about the state of his health when he told them, "I'm well," as he returned to public-facing duties.
Greetings
The royal couple were met by the Chair of University College London Hospitals (UCLH), The Right Honourable Rabbi The Baroness Neuberger and the Chief Executive of UCLH, Mr David Probert.
Warm welcome
Inside the centre, King Charles and Queen Camilla were warmly greeted by clinicians.
Hard at work
The royals heard more about their use of innovative technology at UCLH; including CT scanners which are being used to help with the early detection of cancer.
Meeting patients
The King and Queen meet with Lesley Woodbridge, a patient receiving her second round of chemotherapy for sarcoma, and her husband Roger Woodbridge.
The King sympathised as she received her chemotherapy with many others in a day unit, telling Lesley, 63: "I've got to have my treatment this afternoon as well."
Recovery
King Charles has been receiving care as an outpatient since early February, and sources have said that despite the welcome news the King still has cancer and will continue to be treated for the undisclosed form of the disease.
A friendly face
His Majesty appeared to share some encouraging words with patients during the visit.
When quizzed about his health, he told one patient: "I’m all right thank you very much, not too bad." The development indicated the positive progress Charles is making after almost three months of cancer care as an outpatient.
Exchanging words
The King took the time to hear stories from cancer patients.
Asha Millen, 60, who is receiving chemotherapy for bone marrow cancer chatted to the King. She asked Charles about his own health, saying: "I said, 'How are you?' and he said, 'I'm well.'"
How lovely
His Majesty greeted a well-wisher who presented him with a small bunch of flowers when he departed the hospital.
Farewell
Queen Camilla went on to shake hands with a member of staff as they left the centre.
Initial appointment
In January, King Charles spent three nights in hospital for a procedure on an enlarged prostate, during which his cancer – not prostate cancer – was discovered. After his diagnosis was announced on February 6, the King postponed all public engagements but continued with his duties as head of state behind palace walls, conducting audiences and Privy Council meetings.
Summer diary
The King's diary of events will not be a full summer programme, and attendance will be announced nearer the time and "subject to doctors' advice", with "adaptations made where necessary to minimise risk" to his recovery.
Update
Last week, a palace spokesperson said: "Planning continues for ways in which Their Majesties may attend such Summer and Autumn engagements, though nothing can be confirmed or guaranteed at this stage.
"All future plans remain subject to doctors' advice nearer the time, with appropriate adaptations made where necessary to minimise any risks to His Majesty's continued recovery."