Prince William rushed to be with his wife Kate Middleton after her cancer diagnosis. Kate's troubling health diagnosis is understood to be the reason Prince William missed a memorial service for his godfather, the late King Constantine, which at the time sparked concerns for the Princess of Wales' health.

The palace reported at the time that the Prince of Wales missed the memorial service on February 27 due to a personal matter but did not elaborate further. Constantine died at the age of 82 in January last year, decades after being toppled from the throne in a military coup.

William, 41, reportedly called the Greek royal family to let them know he was unable to attend. Crown Prince Pavlos stood in for William, who had been due to give a Bible reading.

Read more Kate Middleton’s heartbreaking message to George, Charlotte, Louis after cancer diagnosis

Kate revealed that it was only discovered that she had cancer after post-operative tests following her abdominal surgery in January showed the disease. Her condition had not been believed to be cancerous before she went in for surgery.

The Princess is undergoing preventative chemotherapy as advised by her medical team. She said in a statement: "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 found cancer had been present. My medical team therefore advised that I should undergo a course of preventative chemotherapy and I am now in the early stages of that treatment.

"This of course came as a huge shock, and William 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 from major surgery in order to start my treatment."

Kate made her last public appearance on December 25, joining King Charles III, husband Prince William and their three children - Prince George, 10, Princess Charlotte, 8, and Prince Louis, 5 - for the annual walk to Sandringham Church for Christmas morning service.

Prior to that, she had been attending multiple engagements per week before silence. On January 17, Kensington Palace issued a statement about her health revealing she had undergone abdominal surgery and wouldn't return to duties until at least Easter, which falls on March 31.