[heero_yuy]

Unless you explicitly with draw it anybody (like the postie, meter reader etc) has a right to approach your front door by the path that you provide. They have no right to deviate from that path and if you state, in writing, that they may not pass the boundary of your property they commit an offence if they do.

You can also withdraw that right on the spot and they are then obliged to leave immediately. That was the right the police officer was enforcing for your friend.