The third season of “The Crown” welcomes a new cast as it tells the story of the modern British monarchy. The series starts off in the swinging 1960s of London and Olivia Colman is Queen Elizabeth II. Helena Bonham Carter is Princess Margaret and Tobias Menzies is royal spouse Prince Philip. Josh O’Connor and Erin Doherty join the cast as Charles and Anne, the grown offspring of Elizabeth and Philip. Casting and costuming were almost as crucial as the scripts by Peter Morgan.