The BBC’s Watchdog programme warned that the information in the survey, distributed by Doordrop Media, could be used to help criminals burgle your house or steal your identity.

Participants in the survey are asked to fill it in and place it in a marked bag on their doorstep for collection by a courier, who leaves a box of chocolates as a thank you.

Sponsors of the survey include Npower, Unilever and TalkTalk – but TalkTalk told the BBC it would not support any future surveys that required information to be left on a doorstep.

Will Geddes, CEO of security firm International Corporate Protection, said the survey was “a criminal’s charter”. “It defies belief,” he said. “The only thing that’s missing there is a bank account and a sort code.”

The BBC conducted an experiment in which two members of staff filled in the survey, and others then took the information to see what they could do with it. Within 24 hours they managed to set up store accounts, change passwords on mobile phone accounts, order a new phone to be sent to a different address, and have a copy of a utility bill (which can be used to commit further identity fraud) sent to another address.

In response to the television programme Mark Davies, managing director of Doordrop Media, said the firm was committed to “ensuring the highest standards of data security” and that its procedures comply with the Data Protection Act. In the 12 years it has been running, he said, more than two million questionnaires have been returned with no reports of data theft.

But the Information Commissioner’s Office (ICO) said people should “think twice” before leaving this sort of information on their doorstep. “Anyone could potentially pick it up, opening the way to identify theft,” the ICO said in a statement to the BBC.

Doordrop Media said it had developed its methods in consultation with the ICO and security experts to ensure best practice. However, when concerns over the same survey were raised by The Observer three years ago the ICO said it was “clearly not best practice” to ask people to leave forms containing personal information on their doorsteps. Doordrop Media claims that it “worked with the Information Commissioner’s Office to respond to concerns” at that time, but the doorstep survey collections did not stop.

Npower confirmed that it sponsored two questions on a trial basis and was “satisfied that in completing and leaving the TNT survey on their doorstep the customer consented to their data being collected and disclosed in this way and as such adhered to data protection guidelines”. Unilever, which was also listed by the BBC as a sponsor of the survey, could not be reached for comment at the time of publication.

UPDATE 9/11/10
Unilever has sent us the following statement: “The security of our consumers is of upmost importance and we are seeking reassurances from TNT that they are addressing the points made in the programme.”