I've just had an interesting question on the help-line that I thought worthy of a brief article.
I remembered seeing this on the news a while ago and found a BBC article here
Q: My friend who is a landlord has placed a sign outside his property stating "rent dodger lives here". Is this legal?
A: S.40 Administration of Justice Act 1970 states: [highlights inserted by author]
40.Punishment for unlawful harassment of debtors.
(1) A person commits an offence if, with the object of coercing another person to pay money claimed from the other as a debt due under a contract, he—
(a) harasses the other with demands for payment which, in respect of their frequency or the manner or occasion of making any such demand, or of any threat or publicity by which any demand is accompanied, are calculated to subject him or members of his family or household to alarm, distress or humiliation;
(b) falsely represents, in relation to the money claimed, that criminal proceedings lie for failure to pay it;(c) falsely represents himself to be authorised in some official capacity to claim or enforce payment; or(d) utters a document falsely represented by him to have some official character or purporting to have some official character which he knows it has not.(2) A person may be guilty of an offence by virtue of subsection (1)(a) above if he concerts with others in the taking of such action as is described in that paragraph, notwithstanding that his own course of conduct does not by itself amount to harassment.
(3) Subsection (1)(a) above does not apply to anything done by a person which is reasonable (and otherwise permissible in law) for the purpose—
(a) of securing the discharge of an obligation due, or believed by him to be due, to himself or to persons for whom he acts, or protecting himself or them from future loss; or
(b) of the enforcement of any liability by legal process.
(4) A person guilty of an offence under this section shall be liable on summary conviction to a fine of not more than £100, and on a second or subsequent conviction to a fine of not more than £400.
On first glance, it would seem an offence is committed because it states an offence includes: "or publicity by which any demand is accompanied, are calculated to subject him or members of his family or household to alarm, distress or humiliation".
However, on careful reading, it does require the publicity "by which any demand is accompanied". Maybe therefore, if the sign is simply placed up with no demand for payment (most tenancy agreements don't require rent to be formally demanded), maybe the section doesn't apply. I think this is grasping at straws though in an attempt to try and find in favour of landlords!
The other point worthy of particular note is that the offence is not committed "if it is reasonable for the purpose of ... protecting himself ... from future loss" [ss.(3) & (3)(a)].
The final point worthy of note, assuming if convicted the landlord removes the sign promptly, the maximum fine would be £100.00 [ss.(4)] although of course he would also have a criminal record which could affect the fit and proper test should the landlord ever require an HMO licence in the future.