LONDON—Foreign ministers from the Group of Seven wealthy industrialized nations gathered Tuesday in London for their first face-to-face meeting in more than two years, with China high on the agenda. Host nation Britain is keen to show that the rich countries’ club still has clout in a fast-changing world, and has warned that the increasingly aggressive stances of Russia, China and Iran pose a challenge to democratic societies and the international rule of law. U.K. Foreign Secretary Dominic Raab said the meeting “demonstrates diplomacy is back.” U.S. Secretary of State Antony Blinken said engaging with China “from a position of strength … means actually working with allies and partners, not disparaging them.” “It means leaning in and engaging in the vast array of multilateral and international organizations because that’s where so many of the rules are made. That’s where the norms are shaped,” he said. “And if we’re not leaning …