Most landlords I've come across have absolutely no idea that they are obliged to register with the ICO as a data controller and pay an annual fee, or that the punishments for non-compliance are potentially pretty hefty. The few that I've spoken to that were both aware of the requirement and have complied were begrudging to say the least. A couple of days ago I spoke to a landlord who was deliberately avoiding paying by moving everything to do with his rental properties offline. This does seem to be perfectly legal although there are certain aspect of this that are debatable. And it did spark a debate that's worth reading on the LandlordZone Forum
Read for yourselves and decide.