Don't know if it happened in UK or Oz before but it will never happen in Oz now. In OZ it is now law that extra locking devices have to be fitted to prevent theft by terrorists.
The normal door and ignition locks aren't enough. If you don't have an extra approved device you are allowed to lock it to an immovable object with a chain and lock.
All the approved devices I have seen could be bypassed by a ten tear old with a $5 set of bolt cutters from the local discount shop. But I sure I feel much safer now that my R22 isn't going to be stolen by terrorists, loaded with huge amounts of fuel or bombs and flown into the nearest skyscraper. (They need to organise refuelling on their way to the skyscraper - it's only two days flying away!
