The Princess of Wales had a ‘highly unusual’ meeting with a key member of the Royal Family, just hours before she announced to the world she has been diagnosed with cancer.

Princess Kate had a private lunch with King Charles just a day before her shock cancer announcement, which left the monarch quite “emotional”, a source has claimed.

The “highly unusual” heart-to-heart is said to have taken place at Windsor Castle last Thursday as the Princess of Wales was “keen” to speak to her father-in-law about his condition and find out how he was coping.

Charles – who is understood to have been made aware of Kate’s diagnosis before the lunch – travelled from London for the Windsor get-together, which is thought to have included Kate’s video message in its topics of discussion.

The source told the Sun on Sunday: “It is highly unusual for just the two of them to sit down together like this.

“The King had already been made aware that the woman he calls ‘my beloved daughter-in-law’ had cancer.

Princess Kate smiling

Princess Kate had a private lunch with King Charles

“They would have had lots to discuss and share because just weeks earlier the King had begun his course of treatment and dealt with announcing his diagnosis.

“The King left his lunch feeling very emotional. They are very close and he thinks of Catherine as his daughter.

“There is no doubt there is a lot they can share and can use each other for support during their own deeply personal cancer battles.”

Kate and charles speaking

The King and the Princess of Wales are said to be close (Image: Getty)

The Princess of Wales bravely spoke about how she was diagnosed with an undisclosed form of cancer after undergoing “major” abdominal surgery back in January.

Kate added she is now receiving preventative chemotherapy, which she is understood to have started in late February.

She explained that the news came as a huge shock and that it has taken time to “recover from major surgery in order to start my treatment.”

But despite the devastating news, the future queen thanked the nation for “all the wonderful messages of support” and also appeared to spread a message of positivity as she added: “I am well and getting stronger every day by focusing on the things that will help me heal; in my mind, body and spirits.”