If you think you’ll find them on Rightmove, you’re wrong. This market is more analogue. Think postcards in shop windows, paper tear-off strips on lamp posts and word of mouth. Not traceable. Not digital. Not identifiable.

Cash is king in the black market economy. So are the lack of contracts and tenant rights. Forget all the laws the government has introduced to protect tenants, because in this world there are no such rules. These tenants live in a parallel world. A world that Khan cannot even imagine in his air-conditioned office.

For a private landlord who follows the rules – and believes in (most) regulations – it’s a frustrating situation. Keeping up with ever-changing guidelines is expensive. Trying to do the right thing is hard work. But the most infuriating thing is watching and understanding why the rental market is falling apart.

Landlords who don’t want to play by the rules are in for a rich harvest. It’s tempting to think of the money I could make, the freedom to choose my tenants. In the black market economy, you don’t wait years to kick a tenant out. If they don’t pay, they don’t stay.

There is no complicated paperwork, no security deposit considerations, no Section 21, and this market is a simple exchange of money for the use of property.