Season 1 BBC One , 1968 Season 2 BBC One , 1969 Season 3 BBC One , 1970 Season 4 BBC One , 1970 Season 5 BBC One , 1971 - 1972 Season 6 BBC One , 1972 Season 7 BBC One , 1972 - 1973 Season 8 BBC One , 1973 Season 9 BBC One , 1974 Season 10 BBC One , 1975 Season 11 BBC One , 1976 Season 12 BBC One , 1977 Season 13 BBC One , 1978 - 1979 Season 14 BBC One , 1979 Season 15 BBC One , 1980
, 1968