@Fragarach @neil "Legitimate Interest" isn't an intrinsically bad idea.
Remember first that the legislation is around "processing", not "sending you fucking marketing email specifically".
Suppose I run a business and you buy something from it. Later that year, I run an analysis on my database showing where my sales come from broken down by postcode, so that I know where to buy street display adverts.
@Fragarach @neil Is your postcode your data? Yes.
Am I processing it? Yes, to find out where my customers are.
Have you consented specifically to that? No.
Is it necessary for the performance of the contact? No.
Do I have a legal obligation to do this analysis, am saving someone's life, or performing a public task? No.