Article continues below advertisementOK! can reveal Prince William and Kate Middleton are quietly preparing for the responsibilities of the British throne amid mounting speculation that King Charles may abdicate sooner than expected, with sources telling us the Prince and Princess of Wales have begun private briefings designed to ready them for ruling Britain.The renewed scrutiny surrounding the monarchy comes after the arrest of ex-Prince Andrew, which has intensified public attention on the royal family and fueled discussion about the institution's future.