goals in six appearances. Returning to Priestfield, Gillingham were already struggling in the lower reaches of the Championship. Henderson became a regular in the side's struggle for survival, scoring 11 goals. Watford With the 2005–06 season due to start, he became part of Adrian Boothroyd's reshaped Watford side, joining for a fee of £450,000. Signed the day before the first game of the season, he made his début and scored in the 2–1 loss to Preston North End which opened the season. Henderson went on to be an integral part of Watford's successful season in the Championship, scoring 14 goals – nine of which were headers – in 27 games as they finished third, including a splendid half-volley in the local derby away at Luton Town. He also scored a penalty in Watford's 3–0 win against Leeds United in the Championship play-off final, as Watford were promoted to the Premier League. A passionate player, Henderson amassed six yellow cards and one red in the 2005–06 season. While in the Premiership, it was not until 10 February 2007, that he scored his first goal of the season, against West Ham United at The Boleyn Ground in a 1–0. He soon notched his second, hooking in from close range against Wigan Athletic. His final goal of the season came away at Tottenham. In the 2007–08 season, with Watford back in the Championship, Henderson scored thirteen league goals, including five in September. Two of these came in the last 10 minutes against Southampton, as, after coming on as a substitute, Henderson led Watford to victory. Henderson was named as the Championship Player of the Month for September. Henderson continued his good form until Christmas. Only three goals, however, came after the turn of the year. After being suspended for the first leg of the club's play-off semi-final against Hull City, Henderson returned to score the first goal in the second leg at the KC Stadium. However, Watford went on to lose the game 4–1, and 6–1 on aggregate. Henderson had been a highly popular player, and came third in the Player of the Season competition. Sheffield United In July 2008, Henderson signed a 4-year contract with Sheffield United after a fee of £2 million was agreed, with the possibility of further payments depending on appearances. He made his debut for the Blades in a 1–0 away defeat on the opening day of the