About 5,200 burglaries in London due to unlocked doors
About 5,200 homes in London had been burgled last year by thieves who entered through unlocked doors.
To combat the problem the Metropolitan Police (Met) has launched the Lock Before You Leave awareness campaign.
The initiative begins a month before the clocks go back, traditionally a time when there is a rise in the number of burglaries.
The campaign will use radio adverts and Tube station's digital displays, to remind people to lock their doors.
About one in 12 of all burglaries last year was carried out by thieves just walking through an unlocked front door, according to figures from the Met.
Det Supt Martin Rustling, head of the Met's anti-burglary task force Operation Bumblebee, said: "Over half of all burglaries occur through the front door.
"Mostly they are forced, but many are simply opened either from the front, or by putting something through the letter box.
"It's easy to leave your front door unlocked, especially when you're in a hurry or distracted.
"But even if you only do it once, that could be enough to get burgled."