Season 1 ITV1 , 1971 - 1973 Season 2 ITV1 , 1973 - 1975 Season 3 ITV1 , 1975 - 1976 Season 4 ITV1 , 1976 - 1977 Season 5 ITV1 , 1977 - 1978 Season 6 ITV1 , 1978 - 1979 Season 7 ITV1 , 1979 Season 8 ITV1 , 1979 - 1980 Season 9 ITV1 , 1981 Season 10 ITV1 , 1982 Season 11 ITV1 , 1983