 Born in Enfield, London, Morison joined Northampton Town as part of the club's youth system after a successful trial period with the club, having also spent time on trial at Leicester City.When Morison turned 18, he signed a two-year professional contract with Northampton.He impressed manager Kevan Broadhurst and subsequently made his debut at the end of the 2001–02 season in a 2–2 draw against Cambridge United.