 Granada transmitted Thunderbirds in its original , 50 @-@ minute format for the first time with the start of repeats in 1966 . In 1968 , the franchise briefly aired episodes in three parts due to timeslot restrictions . The availability of repeats during the 1960s and 1970s varied among regions . ATV Midlands screened the series regularly into the early 1970s ; by contrast , Thunderbirds was entirely absent from Yorkshire Television between 1968 and 1976 . The series was last transmitted on the ITV franchises in 1981 . 
