When the leaders of the G7 group of nations arrived in France this week for their widely anticipated summit, there was plenty of bonhomie for the cameras. French President Emmanual Marcon and UK Prime Minister Keir Starmer smiled broadly as they shook hands. US President Donald Trump, a well-known sceptic of multilateralism, cut a brooding figure but it did not spoil the businesslike resolve projected by Japan's Prime Minister Sanae Takaichi, German Chancellor Friedrich Merz, Italy's Prime Minister Giorgia Meloni