Overview: We haven't seen the back of Rigsby

It wasn't so long ago that the popular idea of a landlord was not much of an improvement on the appalling Rigsby, played by Leonard Rossiter (right) in Rising Damp.

Then along came buy-to-let and suddenly it was smart to be a landlord. Everywhere you looked, someone was totting up the financial advantages of buying for investment while pointing out that these purchasers were also bringing much-needed rental accommodation on to the market. But does that mean that the Rigsby mindset has disappeared altogether, to be replaced by a more professional attitude?

Not according to one of the country's largest lettings agencies, which has found matters bad enough to warrant setting up a charm school for landlords. Belvoir Lettings, which has more than 80 branches across the UK, has been so alarmed by how casually many of this new breed of investors treat their tenants that they thought it necessary to inform and vet them all in one go. If the landlords prove truculent, Belvoir refuses to take them on.

Mike Goddard, Belvoir's chief executive, has seen for himself how badly landlords can get things wrong. While viewing some flats for sale on behalf of a client, the owner offered to show him around. "He fetched a key, unlocked the doors and walked in." Goddard says. "When I asked whether his tenants had given their approval his response was that, as the landlord, he could go in whenever he chose.

"But he is not alone in believing that owning the bricks and mortar gives him that right. We constantly have to explain that it is the tenant's home and entering without permission is for them as though someone has broken into it."

Belvoir's one-to-one or group sessions, explaining to landlords their responsibilities to tenants as well as other legal and taxation issues, do not always go down well. "If we find the landlords are antagonistic, or refuse to listen to our advice, then we reject them. I would say that overall we reject one in five potential clients."

Goddard makes the point that these "rejects" just go elsewhere - presumably with their attitudes unchanged. "There is a huge, huge mass of tenants who don't get well looked after by landlords," says Goddard. "Instead, they are treated like second-class citizens."

Of course, it makes sense from an agency's point of view not to take someone on their books who is going to cause a stream of complaints. But everyone is aware that there are tenants who feel unable to complain about their homes. They might be students or young people starting out on their own who are simply not familiar with the world of renting, and their first impression of this market can be pretty grim.

Goddard makes the valid point that away from the professional London lettings market with its well-heeled corporate tenants, there is a different world. In it are landlords who have no idea that they cannot withhold deposits on a whim, enter their own property at will, or promise to mend the faulty heating "sometime soon".

But any mention of neglectful landlords tends to bring the big guns in the lettings world rushing to their defence. Until, that is, the big guns' own children become tenants in their own right - then they discover just how ghastly the experience can be for many people. A little bit of charm won't go amiss.