East Sussex was a county of England. The Fourth Doctor, attempting to reach Brighton, instead landed at Fang Rock. (TV: Horror of Fang Rock)
Gatwick Airport was the base of Chameleon Tours, a front company for an alien kidnapping attempt. (TV: The Faceless Ones)
In 2015, the Hyperions surrounded East Sussex with a wall of fire. They filled the area with captured humans that were forced to create components for the fusion web. (COMIC: The Hyperion Empire)
Brighton and Hastings were located in East Sussex.