The Duke of Cambridge said although the moment he and his wife left the hospital with their newborn son was daunting, "We were happy to show him off to whoever wanted to see him".
Prince William said the last few weeks have been "a very different emotional experience" and "something I never thought I would feel myself."
More top news
The talks descended into crisis on Friday when Canada's trade minister Chrystia Freeland walked out of meetings.
Police in New York are still investigating what the substance is and whether it could be harmful.
The Sherlock actor made the comment while he received an award for his humanitarian work.