Complex sentence: It is the most populous British city outside London with 1,085,400 residents (2012 estimate), and its population increase of 88,400 residents between 2001 and 2011 was greater than any other British local authority.
Split into simpler sentences: It is the most populous British city outside London with 1,085,400 residents (2012 estimate). The city's population increased by 88,400 residents between 2001 and 2011, a greater increase than any other British local authority.