 His first two-goal haul of the season came in a 3–0 victory at home to Darlington in the FA Trophy first round on 10 December 2011, scoring Grimsby's first and third goals.It was announced on 23 April 2012 that Coulson had rejected a new two-year contract on reduced terms with Grimsby, meaning he would leave the club at the end of the season.Having been left out of the squad for Grimsby's final two matches of the season, Coulson spoke that he was saddened by the manner of his departure, saying "It would have been nice to go out on a high".