Personal data from the edited electoral register is being sold on to private companies by local councils for as little as £4.50 a pop.
In the last five years, over 300 councils sold information from the register for marketing reasons. Although the register is smaller than the full register, and is opt out, it may not be fully clear to voters - so participating in a representative democracy for many means also handing over personal information to businesses by proxy.
The details are up for grabs for any individual or company.
The cheapest instance was Ryedale Council selling details for £4.50, but others sold information for only £25. In any case, it may not matter to those concerned with privacy whether the data was sold for a penny or £5,000.
A freedom of information request revealed details were bought nearly 3,000 times in the last five years from 307 councils. Between them, the councils earned £265,161.21, privacy campaign group Big Brother Watch said.
Customers ranged from churches to PR companies to pizza shops to universities. Estate agents, insurance firms, financial services, driving schools, and dentists also bought data.
Big Brother Watch is calling for the Edited Electoral Roll to be "junked".
Introduced in 2002, Labour considered banning the sale of such details, but took no action - and the Coalition government has now committed to keeping it in place.
In a statement, Big Brother Watch said: "The sale of personal information by public authorities, particularly for marketing purposes, is something that should never be routine. In the report, we call for the edited register to be abolished.
"We believe that the existence of the edited register impacts on election participation as people are concerned about their personal information being shared for marketing purposes and undermining trust in the electoral registration system."
A spokesperson from the Electoral Commission told the Telegraph it "does not support the commercial sale of any details provided for the purposes of electoral registration" and that it is "concerned that it may act as a deterrent to some people registering to vote".