Season 1 BBC One , 1974 Watch now Season 2 BBC One , 1975 Watch now Season 3 BBC One , 1976 Watch now Season 4 BBC One , 1976 Watch now Season 5 BBC One , 1977 Watch now Season 6 BBC One , 1978 Watch now Season 7 BBC One , 1980 Watch now Season 8 BBC One , 1981 Watch now