Iain Duncan Smith seems to be getting cold feet on the bedroom tax. I am not surprised. This will affect large numbers of people and symbolises the Tories' efforts to wage class war against sections of the population.
In Brent, it is estimated about 550 people would see benefit reduced by about a quarter, and 1,500 people by about 14%. That kind of percentage rise in cost on top of things like Boris Johnson's fare rises and fairly static wage levels will be a disaster for many people.