A Mail on Sunday editor claims she knew Princess Catherine was pregnant with her first child days before the Palace announcement but kept the information to herself, the High Court has heard. Charlotte Griffiths was giving evidence to the privacy trial brought by seven people, including Prince Harry and Sir Elton John, who are suing Associated Newspapers Limited (ANL) - publisher of the Daily Mail and Mail on Sunday - for "grave breaches of privacy". Griffiths said her behaviour was proof she would "draw a line" between her professional and personal life, claiming she had never used a private investigator or hacked a phone. ANL has denied any wrongdoing. Defending her reporting about Sir Elton and actress Elizabeth Hurley, Griffiths argued the information came from sources and not the use of investigators.…