We live in a nice rented house. Been here for three years, no problems whatsoever. We both work full time, have two DC. Just your average family and have never caused any problems! We take most minor maintenance on ourselves as well. Have yearly inspections from the letting agents, however last week after the inspection the LA told me the LL wanted to come inspect the property for himself.
So when he came round, he explained he wasn't happy with the Labour Party poster we have displayed in our front room window. DH and myself are both active in our local Labour Party, and do a lot of leafleting, etc, so are known by the neighbours as the go to people for involvement with the party.
The landlord said he doesn't want his house being used to promote politics, particularly when it's not something he supports himself. 
AIBU to think he has no right to tell us what we can and cannot display when we pay the rent? There is nothing in our tenancy agreement about it, and he is fine with us having photos, paintings and so on hanging on the walls, as well as letting us redecorate to our tastes!