I'm sure Stan is correct, but my 3x great grandmother Eleanor Boullen nee Hastings died as the result of an accident aged 65 and was buried on 22 October 1857 in Ardwick Cemetery, Manchester according to the cemetery burial records. She was living nearby on 3 Ashton Road at the time. I have looked high and low, as has my co-researcher, but neither of us can find either a registration of death or a report of the accident in the newspaper. So I think it's fair to say that some deaths did "slip through the net".
BTW, if anyone else can find her, I'd be eternally grateful!