Absolutely agree with Neville MOrgan and absolutely disagree with Lucy Mori. Unless you live in a high density area with traditional period housing stock, it is difficult to understand what the existing regulations do for poor quality extensions. The majority of the "extensions are us" companies are limited in skills and expertise, cut corners, use unsuitable materials and invariably cause ructions with neighbours. They have no knowledge of planning, building regs and party wall issues and work prohibited hours. London is too densely populated already and older housing stock is being turned into something it was never designed to be. Small terraced houses are being turned into 4 bedroomed houses with unsympathetic dormer extensions and plastic windows overlooking and overshadowing neighbours. Unpleasant and unregulated .