In 2004, they were undefeated at home in the league and made it to the semi-final of the Arriva Trains Cup losing to the eventual winners Leigh Centurions. They also narrowly lost out on promotion to Super League after losing 32–16 in extra time to Leigh in the National League One grand final. The following year despite Castleford being red hot favourites for promotion Whitehaven managed to win their first piece of silverware when he took the National League One League Leader's trophy, however they were unable to take this success into the grand final, where they were heavily beaten by Castleford.