King Charles specifically asked to meet with cancer patients and their families on his return to public engagements

A source told the Sunday Telegraph newspaper: "[The king and queen want to show cancer] doesn't just affect those who have cancer, it affects all those around them.

"Though every patient is different, one of the things they hope to demonstrate and witness is how people can go on living a full life during treatment, not just after it.

"Cancer can be a scary word but it doesn't have to be a scary experience."

The treatment facility being visited by the couple won't be named in advance for security reasons, but Charles and Camilla - who last undertook a joint engagement in November - will meet medical specialists, patients and their families.

No further engagements for the king have yet been announced, but it is hoped he will make an appearance at at least one Buckingham Palace garden party next month, and attend Trooping the Colour, the 80th anniversary of D-Day and Royal Ascot in some form.

Buckingham Palace announced details of Charles' return to public-facing duties in a statement.

It read: "His Majesty The King will shortly return to public-facing duties after a period of treatment and recuperation following his recent cancer diagnosis.

"To help mark this milestone, The King and Queen will make a joint visit to a cancer treatment centre next Tuesday, where they will meet medical specialists and patients. This visit will be the first in a number of external engagements His Majesty will undertake in the weeks ahead.

"In addition, The King and Queen will host Their Majesties The Emperor and Empress of Japan for a State Visit in June, at the request of HM Government.

"As the first anniversary of The Coronation approaches, Their Majesties remain deeply grateful for the many kindnesses and good wishes they have received from around the world throughout the joys and challenges of the past year."

The king has continued to perform state duties, including his red boxes and audiences with Prime Minister Rishi Sunak, behind closed doors while receiving treatment.