Reform of the #NHS has been described as Cameron's poll tax. Having lived through the iniquities of the poll tax - including the fact that wealthy Wandsworth did not charge it - I see the point those making this comparison are seeking to make. But I am not sure it is the correct comparison. I think that NHS reform is Cameron's salt tax.
The salt tax was charged in India - but by the British, of course. http://en.wikipedia.org/wiki/History_of_the_British_salt_tax_in_India (sorry - working in iPad and links are harder). It's relevance was it was introduced with complete contempt for its impact in people, to deny a basic need and to grant a monopoly right to make profit and abuse to a tiny elite.
That makes it a perfect comparison for Cameron's reforms of the NHS. The too are being introduced contemptuously, will deny access to a basic need and have sole intent of granting monopoly rights that will be abused for the enrichment of Cameron's friends.