What do I do if bailiffs show up at the door with a writ for someone who isn't living there?

Tell them the truth! Why do you have anything to hide? Do you know the person in question? Normally a form of ID is enough to make them go away. You can ask them what evidence they have which proves that they live there. It’s up to them to prove that they do live there; and if you own the property you also have the right to deny them entry, though you may want to invite them anyway to prove that there’s nothing to hide. If you don’t own the property, you may want to pass on the details of the visit to the Landlord. The only trouble is that once they’re in, they may not leave until the debt is paid or the missing person is located. That also includes making a listing of possessions on the site. You can also request a copy of the document that the bailiff has and record them if you feel it’s necessary.