NHS ID database
In reply to AC, shhh!
You know this *already exists* - but security is, of course, absolute and excellent!
If you want to be even more secure, you could label yourself as "vulnerable" (which means that only name, date of birth and NHS number are displayed) by getting your GP to fill out and fax through the appropriate forms. (It might be better to check it out on the CfH PDS - Personal Demographics Service - website first - the GP may not have been told about this.) After all, there are, as AC so rightly points out, a *lot* of people with access.. 
Unfortunately, being "sensitive" on PDS will stop you using any of the spine applications - the most important of which is C&B - so in future, as more and more Trusts only accept C&B referrals, you may have to chose between the risk of identity theft or receiving medical treatment.
 the official line has always been that the NHS is one big family, and therefore there is nothing to worry about.
My own feeling is that even the best families may contain a few rotten apples.
Cain and Abel were brothers.