Support each other: King Charles and Sarah Ferguson write heartfelt letters to each other after being diagnosed with cancer. “The King and Sarah are incredibly fond of each other and have now bonded over their respective cancer diagnoses,” an insider tells Mirror.co.uk.

Sarah Ferguson's skin cancer follows breast cancer. Charles' illness must have been very close to the Duchess, because at the event the Duchess thanked her for supporting her family despite her health problems and also wished the King all the best.