To prevent keys being stolen from one's home which seems the rigour with most of these thefts, secure your home. Security windows with bars on the downstairs ones, German Titan Steel Doors (£3000 a pop) with 21 bolts, any glass doors (bad idea) with Security Glass and decent bolts, etc .... Make it difficult, nay 'practically' impossible for them to break-in. Install a good Burglar Alarm, CCTV, etc. In this day and age one can't be careful or secure enough.
Most houses in the UK have terrible security and unfortunately we no longer live in a safe country with low levels of crime, whatever the Govt/Police Statistics spew out.
Sad and worrying state of affairs.