This morning I was trying to think of example reasons for why you'd want to opt out of having your medical records in the NHS's database thing, and whilst I could come up with many theoretical hypotheses, the only concrete examples I could come up with was the possibility of your details being leaked or lost or left on a hard disk on a train along with a few hundred thousand other people's details.
Its not really that convincing, cos in such a case there would be a few hundred thousand other people in the same boat and there'd be a case for some kind of class act.
However, via Dizzy Thinks, we find that Greenwich Council are cross referencing their payrole records with council tax and housing records to see if any of their own staff owes them any money. They have to inform the staff that they're doing such a thing.
Its probably not quite what the council employees had in mind when they took up their jobs, that their employer would be seeking out new and exciting ways of extracting money from them.
So aye, at some point in the future, the NHS could decide to mine their records for anything that could be used to extract more money from you, which is why its wise to opt out.