UK households are being asked to leave sensitive personal information on their doorsteps in the form of a survey on behalf of British companies, it has emerged.
The Household Insight Survey, compiled by TNT Post, is a five-page questionnaire sent to addresses nationwide.
The survey, which features on the BBC's Watchdog programme, asks for details of family birthdays, phone numbers, income levels and mortgage providers.
It gives instructions for the completed forms to be left on the doorstep from where it will be collected the next morning in exchange for a free bag of chocolates.
The survey includes 36 multiple-choice questions with space for information about personal contact details.
Along with details about incomes, mortgages, loans and shopping habits, respondents are asked how frequently they eat out and what months they book their annual holidays.
Mark Davies, the managing director of Doordrop Media, part of TNT Post, said: "The Household Insight Survey has now been running for 12 years. It is fully compliant with the Data Protection Act.
"The collection process has been refined working with the Information Commissioner's Office (ICO) and it is regularly reviewed by leading independent security consultants to ensure that we are following best practice."
Security expert Will Geddes described the survey to Watchdog as a "criminals' charter".
Mr Geddes, who advises companies and individuals on security threats, said he was alarmed at the irresponsibility of encouraging people to leave such information unsecured on their doorsteps.