Re: What leaflet?
You're getting horribly confused there, and the misinformation in your post is staggering. I think you've been reading a lot of scare stories, while not reading up on what is what.
'Red' data (which is first line care only data) is the only one which contains a date of birth and a postcode. Those of course being 'identifying' information. Companies simply can't buy that. To get it, there needs to be a whole horde of legal steps that involve the patient directly..
The first point that a company can begin to acquire information is the pseudonymised "Amber" data, which specifically, in every release that has ever been made about it, specifically mentions they replace the post code and date of birth with tokens. If a country wide research project reveals some worrying spikes in some demographic, that can be reported back to the NHS, who can then refer that back to identify the group at risk, internally (this info can't be passed back to the research group, as it would break the NHS Information Governance restrictions, but it is info the NHS has that is very useful).
Part of the requirement is that any company accessing this needs to abide by an extremely punitive access agreement (the kind that would result in a company being sunk entirely, and the names associated with that company not really being able to work in the industry very easily afterwards).
What you're thinking of is "Green" data, that is pre-aggregated, and contains large scale demographics, without anything that could identify someone (unless you're scared that reporting to your GP for a rash in Manchester in 2013 would uniquely identify you).
Please, don't carry on the scare mongering. There are definitely things to think on about Amber data, and they are being considered.
Now, that's not to say there aren't issues with pseudonymised data; there always will be (any information carries risk). The trick is to balance that risk so society, and its individuals, get the best return for any risk. That's the aim of this, and it's having a fair stab. The debate should _always_ carry on, but it should always be done with facts, not something your mate said in a pub that he'd heard from the dustman who'd got it from his son in the playground from someone who'd read it on facebook, so it must be true!
Have a read of: http://www.england.nhs.uk/2014/01/15/geraint-lewis/ for a quick overview. It's fairly easy to dig out the factual side of things from the official NHS sites, which publish what the data sets contain, and who can access what levels. There's really not a lot of excuse for getting it that badly wrong.