(Re-sent in plain text - I hope)
It's not a stupid question.
When I last raised this on the WDYTYA? Forum, Guy Etchells responded
"The burial register is supposed to record burials not funerals.
"All parishioners had a right to burial in a CofE churchyard, whether
the burial service was conducted under the rites of the CofE or not.
"The law required burials to be recorded not funerals or burial services."
Teresa's point about treating dedicated parts of cemeteries as if they
were part of the church's own graveyard seems eminently plausible and
sensible - I've not seen it in Cheshire, but I've not looked at any
other than my own relatives.
Re closed graveyards - you need to be careful about exactly what
"closed" means. There's closed to any further burials at all and
there's closed to the digging of new graves - the latter allowing
further burials in existing plots.
So while the theory is that it's a burial register not a funeral
register, there may be oddities whose explanation is not clear.