King Charles will be feeling a great deal of "frustration" as he is forced to scale back his royal duties and public-facing appearances amid his treatment for cancer.
A well-placed source said in this week's issue of HELLO!: "His overriding sense will be one of frustration that he will be letting people down because he'll have to cancel a series of planned engagements.
"He will be doing everything he can to take the treatment programme seriously; to get back to full fitness as soon as possible in order to minimize the amount of disruption his personal situation causes to his role as head of nation and state."
Charles, 75, a known workaholic, is only 17 months into the role he waited a lifetime to take on.
Since the news of his cancer diagnosis was announced last week, the King has continued to take his red boxes of official paperwork, has spoken to Prime Minister Rishi Sunak by telephone, and also sent a message of congratulations to the people of Grenada as they marked half a century of independence, writing: "I can only say how sorry I am that I cannot be with you in person to mark this momentous milestone and to enjoy a little Oil Down [stew] with you all!"
He has had to cancel various public-facing engagements though, since starting his first round of cancer treatment. And Charles will rely on his elder son and heir, Prince William, to represent him and the monarchy when required, just as he did for his mother, Queen Elizabeth II.
"I think William has certainly realised this and the weight of the world is on his shoulders. He's going to be the King at some stage," royal author Robert Jobson also told HELLO! this week. "The expectation is on William's shoulders and he must be feeling rather like Her late Majesty Queen Elizabeth when she was 25, suddenly being catapulted into this job which becomes all consuming."
William, 41, is expected to step in to carry out in-person engagements. He and his father are in regular contact.
But Charles' diagnosis comes at a tricky time for the Wales family, given that William is also helping to care for his wife Kate, who had planned abdominal surgery last month and is expected to be out of action until Easter.
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