 <unk> to distinguish his 26 @-@ episode proposal from APF 's earlier productions , Anderson attempted to pitch stories at a level that would appeal to both adults and children . Whereas previous series had been shown during the late afternoon , Anderson wanted Thunderbirds to be broadcast in a family @-@ friendly <unk> slot . Sylvia remembers that " our market had grown and a ' <unk> ' show ... was the next step . " The Andersons retired to their holiday villa in Portugal to expand the premise , script the pilot episode and compose a <unk> ' guide . According to Sylvia , the writing process depended on a " division of labour " , whereby Gerry created the action sequences while she managed characterisation . The decision to make a father and his sons the main characters was influenced by the premise of <unk> , as well as Sylvia 's belief that the use of more than one heroic character would <unk> the series ' appeal . The Tracy brothers were named after Mercury Seven astronauts : Scott Carpenter , John Glenn , Virgil " Gus " <unk> , Gordon Cooper and Alan Shepard . 
