Network SouthCentral covered most of Sussex and parts of East Surrey. The core of NSC's operations was the Brighton Main Line, with most other NSC mainline services utilising some part of this alignment. The rough boundaries of the NSC operations were from Hastings in the east to Portsmouth in the west, although services operated by the company did extend further on both sides to Southampton along the West Coastway line in the west, and as the sole operator of the Marshlink line from Hastings to Ashford via Rye.