Following the Mid-Staffordshire patient care scandal, Professor Don Berwick was tasked with conducting a review into patient safety and recommended medical staff face prison for unacceptable treatment.
Speaking in August, Prof Berwick said, "Wilful, reckless, negligent behaviour - that deserves punishment".
More top news
The author said "It's been wonderful" as fans mark two decades since the children's books opened up a world of magic to millions.
There was something very striking about the pact, which implies the new agreement could remain in place even if the prime minister does not.
The royal will visit the site of the deadly attack at Manchester Arena as he remembers those killed and injured.