The police in Bishop Auckland are offering people who buy a new bike from Halfords in the town the opportunity to get their bike marked. This will hopefully allow a bicycle to be returned to the owner, should it get stolen. See the link below for more details, from the Northern Echo:
I'll have to enquire about getting my bikes marked as I haven't thought about until I read the article.
For tips on how to prevent your bicycle from being stolen in the first place, have a read of a previous post about locking a bike securely.