J_smudger 24 January 2014 3:00pm
I think there is confusion amongst some commenters here. This comes from reading a large amount of literature from the relevant pages on the NHS / Health and Social Care Information Centre (HSCIC). The HSCIC are basically a repository in Leeds, where all this information will be stored.
Your GP records are going to the HSCIC as pseudoanonymised information, which as has been said does indeed include your NHS number, date of birth and postcode. The HSCIC will then build up a database of this information. They can indeed pass on certain of this information to certain external interested parties, although when they do this the data becomes truly anonymised as opposed to pseudoanoymised. You can read about this in the NHS published guidelines (although not in the rather patronising leaflet), as well as from the documentation of the HSCIC and the government itself.
To quote the HSCIC:
we take out details that could identify you before we make any information available
At the NHS: there are no personal details such as your date of birth and postcode included... We would never publish this type information because there is a risk that you might be identified.
The HSCIC can only release identifiable information when (1) you specifically ask them to, or (2) hypothetically, when there is a national emergency such as a highly virulent pandemic. This would require a legal process.http://www.nhs.uk/NHSEngland/thenhs/records/healthrecords/Pa...
http://www.hscic.gov.uk/article/3399/Rules-for-sharing-infor...
Or if you have a hour to spend read this:
http://www.hscic.gov.uk/media/12931/Privacy-Impact-Assessmen...
... or perhaps just sections 3.3.4. and 3.3.5.