On a more "constructive" tack, I think the underlying problem is the over-reliance on individual private investors to cough up the money to provide rental housing.
If you read the articles on the Council of Mortgage Lenders website you will see that there is total commitment to the notion of providing more rental accommodation through private investment rather than institutional investment (the assumption being that public money will not be a significant contributor towards housing construction in the foreseeable future because of the state of the economy).
I think this is wrong, because it puts the profit motive above all other considerations. Governments should be operating on a higher moral plane than that. They should be using taxation as a means of influencing such matters - making it more favourable for institutional investors to deliver rental housing and less favourable for individuals to do so.