DMcG I think you attach a reliability to the cause of death on a certificate that simply does not exist.

You are free to think that if you wish. I don't, because I have been dealing with data uncertainty for a very long time indeed. Pretty much all my working life has involved data of dubious quality, inconsistent definitions, different people interpreting the same rules in different ways and so on and so forth. But that's what you think, fine by me.