The rebuilding of London after WW2

  The Blitz was definately the most traumatic experience of all Londoners that lived during World War II. And even when the bombing ended the problem didn't disappear, because great part of London was totally destroyed and many, many people were left without their homes. But as a lot of people know that "every cloud has a silver lining" that became an opportunity of changing something in London's architecture.
  The most popular planner of that period was Patrick Abercrombie. His main idea was to reconstruct the capital to create a balance between housing, industrial development and open spaces. He also wanted to encircle London with some "green spaces" such as parks, recreation grounds, farmland etc. The whole idea was called "County of London plan".

*the first public building to be constructed after the War was The Royal Festival Hall on the Southbank

                           Patrick Abercrombie

Source: 

http://www.history.co.uk/study-topics/history-of-london/ww2-rebuilding-london