The Rock’s Chief Minister was pictured with May and his deputy Joseph Garcia in 10 Downing Street today.
Attorney General Michael Llamas joined the trio as meetings were held about Iran’s detained Grace 1 oil tanker.
British Royal Marines commandeered the vessel off the Rock earlier this month on suspicion of violating sanctions against Syria.
Meanwhile, May, who resigned after failing to get her Brexit deal through Parliament, praised Picardo for his sensible, ‘level-headed and pragmatic approach’ to Brexit.
A Gibraltar Government spokesperson added: “The Chief Minister thanked Mrs May for her unwavering and solid support for Gibraltar during her time in office.”