Protesters marking the death of Baroness Thatcher in Trafalgar Square broke out into song and cheered when an effigy of the former Prime Minister made its way through the crowd.
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.