Through economic booms and slumps, the supply of housing has failed to keep pace with demand. The political solution to this problem has consistently focused on the supply side of the equation. The speed of the economic downturn in 2007/8 left many developers with extant planning permissions for residential developments across the country. The Government believes that if it can persuade developers to 'get Britain building' this will provide a Keynesian kick to the economy and go some way to addressing the supply and demand mismatch. But as moribund economic conditions continue, it is clear that sites are not being developed in significant numbers; they are "stalled". But why are they stalled, how many dwellings do they represent, where are they and what sort of housing schemes are involved? Organisations such as the Local Government Association and the Campaign for the Protection for Rural England have argued that the supply of housing sites is adequate with planning permission for over 400,000 housing plots unimplemented. The typical opposing view from the House Building Federation is that "Too many sites are now 'under water' due to charges levied on them by central and local government.