I found one on my letter box last week, I was worried so called the number suggested by the bbc website and they said that I shouldn't worry, that so so many people have had stickers on their door and nothing has happened they are not even sure its linked to robberies at all anymore. he even suggested it never was?
I then looked down my street and everyone had a sticker !? Talk about subtle.
On top of that my house is very secure, I have a massive rottweiller and Im constantly at home as 38 weeks pregnant.
I think those stickers are nothing to worry about.