A scene from “Unfinished Business”

Tommy Lascelles: [flashback, after a young Margaret suggests taking Elizabeth's place as heir] What you are suggesting is unthinkable. The order of succession to the throne is determined by the Act of Settlement of 1701, not the wild and irresponsible whims of young princesses. The principle of undisturbed hereditary descent is a pillar of stability and perpetuity for the nation. Princess Elizabeth's destiny is to accede to the throne. Yours is to serve and support. I would urge you to accept your position in life ... and to dismiss forthwith any childish notions about rewriting the rule books that it might better suit your character. We all have a role to play. Princess Elizabeth's will be center-stage, and yours, ma'am, will be from the wings.