Shortly before production was due to begin on series six, Yootha Joyce died suddenly from liver failure on 24th August 1980, aged 53. The sitcom was cancelled.
Norman Eshley, cast as Geoffrey Fourmile, previously appeared in an episode in the progenitor series Man About the House (1973) as Robin's brother Norman. Norman also appeared in the last 3 episodes of series 6 of MATH. Bizarrely, neither George or Mildred mention that Geoffrey looks like Norman. Fan theories suggest that either they really weren't in close contact to him, or they say nothing in case it was some dark Tripp/Fourmile family secret.
Despite Yootha Joyce's serious alcoholism (which led to her early death at 53 in 1980), co-star Brian Murphy stated that she never allowed it to interfere with or adversely affect her performances during the series' production.
During the series' production, Nicholas Owen (Tristram) announced that he was legally changing his name (with his parents' permission) to Nicholas Bond-Owen as he was a huge fan of "James Bond".