Complex sentence: After the Isthmian League First Division was divided in 2002,they were placed in Division One (North), and won the championship of that league in the 2003-04 season, returning to the Premier Division.
Split into simpler sentences: After the Isthmian League First Division was divided in 2002 they were placed in Division One (North). They won the championship of that league in the 2003-04 season, returning to the Premier Division.