The 75-year-old monarch -who is currently undergoing treatment for an undisclosed form of cancer- and his wife will be at the religious service at

St. George's Chapel

this Sunday (31.03.24) morning, the Palace has confirmed.

It will be the king's first significant public appearance since he announced his diagnosis in February, but the Palace also confirmed his daughter-in-law

Catherine

, Princess of Wales and her husband

Prince William

will not be in attendance following her shock cancer announcement at the end of last week.

The 42-year-old royal - who is married to Prince William and has

Prince George, 10, Princess Charlotte, eight, and five-year-old Prince Louis

with him - has been absent from public duties since January and announced on Friday ( 03.22.24) evening that she is battling a form of the disease.

She said: "I wanted to take this opportunity to say thank you personally, for all the

wonderful

messages of support

and for your understanding while I've been recovering from surgery. It has been an incredibly tough couple of months for our entire family. But I've had a fantastic medical team who've taken great care of me for which I'm so grateful.

"In January, I underwent

major abdominal surgery

in London. And at the time, it was thought that my condition was non-cancerous.

"The

surgery was successful

. However, tests after the operation on cancer had been present.

"This of course, came as a huge shock. And Wiliam and I have been doing everything we can to process and manage this privately

for the sake of our young family

.

"As you can imagine, this has taken time, it has taken me time to recover for major surgery

in order to start my treatment

."