Season 1 BBC One , 1966 Season 2 BBC One , 1966 - 1967 Season 3 BBC One , 1967 - 1968 Season 4 BBC One , 1968 - 1969 Season 5 BBC One , 1969 - 1970 Season 6 BBC One , 1970 - 1971 Season 7 BBC One , 1971 - 1972 Season 8 BBC One , 1971 - 1973 Season 9 BBC One , 1973 - 1974 Season 10 BBC One , 1974 Season 11 BBC One , 1975