Complex sentence: The 2012 census found that, for the first time, less than 50% of London's population were white British, and that in some areas of London white British people make up less than 20% of the population.
Split into simpler sentences: The 2012 census found that, for the first time, less than 50% of London's population were white British. IN some areas of London white british people make up less than 20% of the population.