British activists upset about President Trump’s state visit this week protested his arrival by projecting a picture of Mr. Trump with Jeffrey Epstein on the walls of Windsor Castle and unrolling a massive banner of the picture on the castle’s grassy lawn. The president and Melania Trump, the first lady, arrived in London on Tuesday night. They are scheduled to spend Wednesday at Windsor Castle, hosted by King Charles III and Queen Camilla. Mr. Trump will also meet Prime Minister Keir Starmer at his country residence, Chequers, on Thursday. The banner was created by the group Everyone Hates Elon, which was behind similar protests in Britain against Elon Musk, the billionaire tech mogul.