The U.K.’s “sluggish” growth prospects have put it on course to be the worst-performing economy of all advanced nations next year, according to new forecasts from the Organization for Economic Cooperation and Development. U.K. gross domestic product is expected to grow 0.4% in 2024, the Paris-based think tank said Thursday in its latest global economic outlook. That figure is down from a previous prediction of 0.7% and less than all other G7 countries besides Germany, which is expected to be 0.2%.