Season 1 BBC One , 1971 Season 2 BBC One , 1972 - 1973 Season 3 BBC One , 1973 - 1974 Season 4 BBC One , 1974 - 1975 Season 5 BBC One , 1975 - 1976 Season 6 BBC One , 1976 Season 7 BBC One , 1977 Season 8 BBC One , 1978 Season 9 BBC One , 1979 Season 10 BBC One , 1980 Season 11 BBC One , 1981 - 1982 Season 12 BBC One , 1990 Season 13 BBC One , 1991 Season 14 BBC One , 1992 - 1993 Season 15 BBC One , 1993 Season 16 BBC One , 1994 Season 17 BBC One , 1995 - 1996 Season 18 BBC One , 1996 Season 19 BBC One , 1997 - 1998 Season 20 BBC One , 1998 - 1999 Season 21 BBC One , 1999 - 2000 Season 22 BBC One , 2000 - 2001 Season 23 BBC One , 2001 - 2002 Season 24 BBC One , 2018
, 1971