Mel Cappe, a former Canadian minister and senior civil servant, has been involved in preparing such speeches from the throne, usually delivered by a governor general. He expects the King to add a "few paragraphs of his own at the beginning" to "give his own personal view", but the overall text of the speech will be approved by Canada's prime minister and his officials. "He's not going to poke President Trump in the eye. That would cause a problem for Canada. On the other hand he isn't going to suck up to Donald Trump," says Prof Cappe, who was also a high commissioner to the UK. He believes this intervention could have a big impact: "Symbolically this is huge. President Trump has a lot of admiration for the monarchy. He is impressed by the royals." This royal moment will be a platform for Canada's government to talk about tariffs and to mention the visit to the White House where PM Carney said Canada would "never" be for sale, says Prof Cappe. "So somewhere in that speech, look for the word "never"," he says. President Trump, as shown in his recent controversial White House meetings with South Africa's President Ramaphosa and Ukraine's President Zelensky, can be an unpredictable diplomatic partner. "The old alliances are breaking down," says Mr Kinsman. And against a background of such uncertainty, King Charles has been part of an unexpected international balancing act. He became a key part of the charm offensive to maintain the UK's good relations with President Trump, with an invite for a second state visit. Now he's going with a message of reassurance to the Canadians. Sir Keir Starmer has been using the King to get closer to Trump, while Mark Carney is using him to keep Trump further away. "He isn't anybody's tool or fool. This is something that he believes… It genuinely is something that he wants," says Mr Kinsman about the King's support for Canada. The former diplomat remembers how much the then Prince Charles showed a personal affection for Canada and a sense of duty towards its people. A planned trip last year had to be cancelled because of his cancer diagnosis.