Season 1 BBC Two , 1971 - 1972 Season 2 BBC Two , 1972 - 1973 Season 3 BBC Two , 1973 - 1974 Season 4 BBC Two , 1974 - 1975 Season 5 BBC Two , 1975 - 1976 Season 6 BBC Two , 1976 - 1977 Season 7 BBC Two , 1977 - 1978 Season 8 BBC Two , 1978 - 1979 Season 10 BBC Two , 1980 - 1981 Season 11 BBC Two , 1981 - 1982 Season 12 BBC Two , 1982 Season 13 BBC Two , 1983 - 1984