When one reads something by a person termed a “royal expert” or “royal insider”, one normally expects to be served 80 per cent speculation by someone the Princess Royal once told to “naff off”. This is not so with Robert Hardman. For a quarter of a century, he has earned the respect of the Royal family and their household by telling the truth, exercising discretion, avoiding sensationalism and acquiring a deep understanding of the institution and its history. His books and television programmes on the functioning of our monarchy are therefore highly authoritative and laden with insight, and this latest, Charles III, is no exception. Hardman never over-sells himself or his work. Beginning this book on our King, the author says that “I have not sought to write a full-life biography. This is a contemporary portrait of our new monarch, and his new court.” And he proceeds to do exactly that, in Rolls-Royce fashion.…