This document discusses factors that have impacted population changes in London over the past 400 years. It mentions improvements in transportation allowing London to grow outside the central city as people could commute to work. It also notes that large numbers of factories in London attracted more workers and encouraged additional development. The document further discusses people migrating to London from other parts of the UK and world in search of jobs, and how the perception of London has changed over time due to regeneration and increased tourism.