The anonymous blogging policeman records that officers are visiting areas with high vehicle crime and identifying vulnerable vehicles. They attach a sticker to the windscreen informing the owner that there is some kind of insecurity. They even tick a box telling the owner how the vehicle is insecure. This marks out the vulnerable cars for thieves and helpfully informs them how to proceed.
As the blogger says: "This is quite the maddest scheme in British policing."
Mark