[[WMG: Sheridan is [[DeadAllAlong quite literally]] TheGhost]]
Yep, just like in ''WhosAfraidOfVirginiaWoolf'', the apparently miserable couple whose long marriage [[NoAccountingForTaste no-one can understand]] is entirely founded on their mutual denial of the loss of the one good thing they ever had. Although that doesn't explain why they imagine him to be an AmbiguouslyGay, profligate wastrel...
* Granted, it would present a challenge for a ghost to use the telephone.
* Well, in the Swedish novel ''The Dung-beetle Flies at Dusk'' the kindly old lady who has periodically been phoning up the protagonists with helpful if slightly cryptic hints turns out to have been DeadAllAlong...
* Perhaps every now and then someone about his age, or who sounds like him, calls up ordering Chinese food. Hearing their voice causes Richard and Hyacinth to slip into denial and start talking to them as though they were their son, leaving a very confused person on the other end of the line. Perhaps when he was alive they fought over the fact that he was wasteful with money and could never accept the fact that he might be gay. Now they just imagine him always asking for money so they can always send it to him and always dropping hints about his sexuality so they can always "accept it" as a way to assuage their guilt.
[[WMG: Keeping Up Appearances shares a universe with RumpoleOfTheBailey and Hyacinth is actually Hilda's niece]]

This is inspired by a couple of observations. Firstly, the first time I saw Peggy Thorpe-Bates with a particular haircut and from a particular angle I mistook her for Patricia Routledge (there’s an age difference but the episode of Rumpole was made several years before Keeping Up Appearances).

Secondly, the characters do have some significant character traits in common. Both call their father's "Daddy" in a near identical tone of voice. Both are stern-voiced social climbers whose major obsession is to get their husbands, who have no social aspirations, to greater social positions.

Also, while Hilda’s family certainly seems to have more money than Hyacinth’s, the differences are no greater than those between Daisy/Rose, Hyacinth and Violet.

[[WMG: The sisters' maiden name really was "Bouquet." Also,Richard's last name is really "BUCKET."]]

This would explain the floral-theme to their names. Also, when Hyacinth and Richard got married, it would allow her to use the "bouquet" pronouncation.