Two million Brits are playing into the hands of burglars by leaving written copies of bank and credit card PINs lying around their houses and wallets.
Burglars have admitted they seek out card PINs when ransacking homes a property. One interviewed for research commissioned by Churchill Home Insurance said: "I do look for bankcards and PINs for bank cards… you can take them straight to the cashpoint."
Another said: "There were a few times we found PIN numbers. We would go shopping with them."
A further two million people leave their passports and other important financial documents, such as mortgage statements, in plain sight around their homes.
The thieves also revealed that the nation's favourite hiding place for valuable documents is underwear and sock drawers, with six million of us admitting to tucking away our paperwork in them.
Food containers, such as cereal boxes, and the fridge-freezer are among other supposed 'secret' locations.
One burglar told the insurer: "Old fish finger boxes in the fridge... that is the first place you would look for something they don't want you to find".
Other 'hideaways' for documents include books, the loft and taping them to the bottom of drawers.
The theft of documents can lead to grave financial consequences. One thief admitted: "We would look for paperwork and ID to sell on. You would look for paperwork for mortgage [sic] and passports and sell it on to those in the know."
As for other valuables frequently targeted during robberies, the burglars revealed that relatively simple security measures such as Apple's 'Find my iPhone' serve as better deterrents than passwords.
One thief said: "Passwords for electricals do not worry me, that can easily be got around, except Apple items which I just avoid stealing altogether.
"Apple have this thing with iPads where you can register your device and… if it is stolen can track you down. I think this is something I have just become aware of myself because I am into gadgets. But Apple had done well with that; I think it is a real deterrent."
Another added passwords on laptops don't act as any real deterrent. He said: I can pay £10 and get a laptop unlocked."
A fellow convict added: "If you have a laptop you do not need to worry because you can just press two keys and wipe the hard drive or just replace the hard drive depending on how valuable it was."
Martin Scott, head of Churchill Home Insurance, said: "In an increasingly digital world it can be difficult to keep track of all of the PINs and passwords required to access our personal information. By creating physical copies of these details and leaving them in an accessible place, people are offering criminals instant access to highly sensitive information."
He added: "It's not just about TVs and laptops, burglars are now very astute when it comes to selling documents. To keep personal details safe, people should store the most valuable ones such as passports and mortgage documents in safes or at the bank."