Complex sentence: Winston Smith is an intellectual, a member of the Outer Party (middle class), who lives in the ruins of London and grew up during post-World War II England, that is, following the revolution and civil war, after which the Party assumed power.
Split into simpler sentences: Winston Smith is an intellectual member of the Outer Party (middle class), who lives in the ruins of London and grew up during post-World War II England. It takes place during the revolution and civil war, after which the Party assumed power.