The Thunder reached the BritBowl Final in their second year led by current Head Coach Ian Ellis, narrowly losing to the London Olympians.

Success continued to allude the club afterwards, but on 20 September 2008, led by Head Coach Len Scott, the Thunder won the Division 1 national championship in an overtime win against the Redditch Arrows.

In November 2009, the Sussex Thunder appointed ex-San Francisco 49ers trialist Tony Stitt as head coach and under his guidance won promotion back to the Premier Division of the BAFA National Leagues.

A Play-off run followed in 2011 (where they lost to the Birmingham bulls 14–13) before the club once again claimed the Division 1 National Championship in 2012.

Membership was approved by the league and in 2015 the team re entered the Division 2 South East Conference.