Despite Kirk scoring on his debut, Northampton lost to Rushden & Diamonds and a stuttering finish to the season witnessed them fall in the play-off semi-finals. The following season, Kirk's 10 goals ensured there was no repeat and Northampton gained promotion to League One. During the 2006–07 season Kirk was transfer listed alongside fellow strikers James Quinn and Scott McGleish. However, Kirk was taken off the transfer list at the beginning of the 2007–08 season and rewarded manager Stuart Gray with 3 goals in the first 3 games.