11 hours ago Sean Coughlan Royal correspondent, Washington DC Jordan Pettitt - WPA Pool/Getty Images The US state visit takes place at a time of "very unusual" political tensions "It's high risk, high stakes and high opportunity." That's how a royal source describes next week's state visit by King Charles III and Queen Camilla to the United States. There is genuine jeopardy in this US trip. It's not just a grip-and-grin photo opportunity, with some warm words and a few celebrities hitting the embassy prosecco. "The visit comes in the biggest crisis in Anglo-American relations for a century," says Andrew Lownie, author of the best-selling biography of Andrew Mountbatten-Windsor. "We're dealing with a very unpredictable president," says Lownie. But if anyone can influence Trump, he adds, it's King Charles.…