Thunderbirds is a British science fiction television series first broadcast during 1965 and 1966 which was devised by Gerry and Sylvia Anderson and made by their company, AP Films, using a form of marionette puppetry dubbed "Supermarionation". The series followed the adventures of International Rescue, a secretive organisation created to help those in grave danger using technically advanced equipment and machinery launched from its hidden Tracy Island base. The series focused on the head of the organisation, ex-astronaut Jeff Tracy, and his five sons who piloted the "Thunderbird" crafts. Its London agent, Lady Penelope, also makes frequent appearances. The series has benefited from periodic revivals since - as well as subsequently inspiring other television programmes and advertisements, theatrical productions, feature films and substantial merchandise.