Two million Britons regularly leave an external door unlocked when they are out of the home, and one in one-in-four successful burglaries, thieves let themselves in through an unlocked door.

Householders take the least care with their back door, as 1.3 million people regularly go out leaving it unlocked, said Halifax Home Insurance.

Responding to its findings, the insurer warns householders that external doors provide the entrance point for 68% of burglaries.

Ensuring all external doors are locked when a property is unoccupied is a simple but crucial step to reduce the risk of burglary. Indeed many burglars will spend no longer than 60 seconds trying to break into a home.

Reasons given for leaving doors unlocked when out of the property included:

• a belief that neighbours were watching the property (18%)
• perceiving the area they lived in as having low crime (18%) and regularly forgetting to lock doors (10%)
• 3% leave their door unlocked because they feel that they don’t have anything worth stealing

Reformed burglar Bob Turney, now a probation officer said, "The average household contains around £3,000 to £5,000 worth of items that are easy to steal - such as laptop computers and mobile phones."

17 million Britons also think it’s safe to leave an external door unlocked whilst inside the home, and do so in the belief that their presence is enough to make their home secure. Contrary to this notion Halifax Home Insurance points out that the majority (55%) of UK burglaries actually take place while a resident is still inside the home.

Vicky Emmott, senior underwriter at Halifax Home Insurance, commented: "With street crime rising by 8% this year the idea that any street in Britain is safe enough for you to leave your door unlocked is little more than a nostalgic notion. But judging by the findings of our report millions of Britons still live in the past."

"Locking doors is such an effortless action and yet it probably provides the most effective deterrent to any thief. Householders should be aware that leaving a home unlocked when it’s unoccupied could invalidate a home insurance policy – leaving the homeowner to pick up the pieces alone."

"Householders should also be increasingly aware of the security risks of leaving doors unlocked even when they are in the home, especially since today’s burglars seem less worried about whether you are in or out. The simple rule is to keep all external doors locked at all times."

Almost one in ten (9%) adults living in Greater London regularly leave their home unlocked when the property is unoccupied. People living in Wales & West (9%), Scotland (8%), followed by the North West (7%), usually leave doors to their home unlocked when they are away from the property.