from the daily mail......
"While 'old age' can be listed as contributing to a death, official guidelines state it should only be used as sole cause of death in very limited circumstances.
There is no official age limit for saying someone died of 'old age' but it is generally only accepted if the person is over 80.
The doctor should also have cared for the deceased for years or months and noticed a general decline in their health, as well as their functioning in day-to-day life.
There must also be no obvious identifiable disease or injury that contributed to their death, though 'old age' can be listed as contributing factor.
The final official condition for using 'old age' as the cause of death is that the doctor is 'certain' there is no reason that the death should be reported to the coroner for further investigation.