With the urgent need for more housing, Britain's planning laws are under pressure like never before. Greenbelt land and even sites designated as Areas of Outstanding Natural Beauty, are being earmarked for development. So how far can we protect the countryside when the need for houses is so acute? Allan Urry reveals new figures on scale of the problem and investigates claims that the planning system is being stretched to breaking point. Reporter: Allan Urry Producer: Emma Forde.