Kate and the King had a heart-to-heart at Windsor Castle hours before she announced she had cancer.  Charles , travelled from London for a private lunch with his "beloved daughter-in-law" Kate on Thursday.Kate wanted to speak to Charles  about his struggle and find out how he was coping.It is believed the pair also talked about Kate's video announcement in which she said the discovery was a "huge shock" but vowed she was "going to be OK".A source said of the Windsor Castle get-together: "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."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."It was an emotional meeting for both of them, but also a chance to support each other and share their experiences. The King has been a rock for Kate during this difficult time, and she wanted to be there for him as well.""Despite the challenging circumstances, there was a sense of closeness and understanding between them. They both know what the other is going through, and that shared experience has only strengthened their bond."