Full disclosure here first - I own a rental property with DH, we're small business owners & its part of our savings plan for retirement.
I totally agree that the Housing benefit bill is out of control. There doesn't seem a cats chance in hell that there is going to be mass building or buying of social housing (whether HAs or council houses). So most people who don't own their own house are going to be living in private rental properties.
This means that most housing benefit paid goes to private landlords. We're also in a high house price/high rent spiral where people can't afford to buy, so there's lots of upward pressure on rents.
Planning laws (which I largely support) mean that we already don't have anything resembling a free market in housing / house building. So might the least-worst situation be rent controls?
I'd envisage a fairly simple broad sweep control whereby a maximum rent is set for a local authority area of £X per month for a 2 bed property, £Y per month for 3 bed etc.
Then say a 'rent review' body where landlords could appeal (at their cost) to argue that there is some reason why their particular property should be exempted from the maximum, eg if it is a luxury flat. That body could then give the go-ahead for eg a rent of 10% over maximum for that property.
Come and flame me one and all :)