Prince William and King Charles III once clashed over a difficult topic - which led to the heir to the throne being forced to sign a 'waiver'. This is according to Robert Jobson's 'revelatory' new biography, Catherine, The Princess of Wales, which focuses on the life of Princess Kate so far, from ordinary university student to mother of three and Queen in waiting. According to royal correspondent Jobson, this row occurred following King Charles' cancer diagnosis, which saw him take a temporary step back from his official duties.

It's believed his own mortality, as well as the future of the monarchy, was no doubt weighing heavily on Charles' mind as he reprimanded his eldest son on a difficult topic. Like his later mother Queen Elizabeth II, King Charles had grave concerns about experienced pilot William's decision to fly his young family around the country in a helicopter. Plagued with terrible memories of the 1967 crash that killed the Captain of the Queen's Flight, senior royals expressed serious fears over the Wales family's welfare - not to mention that any similar tragedies would disrupt the line of succession in explosive ways.

In a passage published by the Mail Online, Jobson wrote: "After being diagnosed with ­cancer, King Charles — perhaps reminded of his own mortality — echoed his late mother’s concerns. And when William refused to stop flying with his family, Charles insisted that he sign a formal ­document, acknowledging the risks involved and taking full .