I attended a presentation by Sir Howard Davies about U.K. airport capacity 18 months ago, and the case for another R/W at EGLL. An extremely knowledgable member of the audience asked him about noise limitations, and why the present restrictions were still based around the operation of Tridents, 707s and VC10s?
SHD didn't have an answer. It's time to move on. Road traffic generates more noise than modern jet aircraft.