league title in twelve years and O'Callaghan picked up a winners medal. He scored eleven goals in all competitions, including in the 2005–06 UEFA Cup, and was also announced as the eircom League Player of the Year for 2005. He also played in the 2005 FAI Cup Final defeat to Drogheda United at Lansdowne Road. He also was named as League of Ireland Player of the Year. In July 2006 he was given time off due to a falling out between himself and manager Damien Richardson. In September 2006, O'Callaghan joined English club Ipswich Town on trial with a view to a permanent deal. He remained training at Ipswich for the following two months, unable to formally sign because of UEFA's transfer window system. In January 2007, the clubs finally negotiated a deal despite strong words on both sides, concluding in an undisclosed fee (speculated to be around £60,000) which saw him sign an eighteen-month contract with Ipswich. On his full Ipswich debut he was sent off playing in the FA Cup against Watford, after an alleged stamp on defender Danny Shittu. However O'Callaghan was to escape a further three match ban after a successful appeal. On 7 May 2007, O'Callaghan scored his first goal for the "Tractor Boys" in the 5–1 win over Barnsley. In August 2007, Ipswich agreed terms with Brighton & Hove Albion to sell O'Callaghan for around £85,000, rising to £105,000 based on appearances, although this transfer fell through as the club and player were unable to reach an agreement on personal terms. He did however move to Withdean on loan until the end of December 2007. He rejected the chance to sign permanently at Brighton, stating that chairman Dick Knight was being unrealistic with the wages he was offering both himself and fellow striker Bas Savage. Both players left the club at the end of December 2007. In January 2008 he decided to terminate his contract with Ipswich, having played seventeen games for the club, manager Jim Magilton explained: "George is a great lad but he's 28 now and needs to be playing regular first-team football. We have not been able to give him that here and we won't stand in his way of moving on now." On 31 January 2008, O'Callaghan returned home to Cork City, signing a three-year deal under new manager Alan Mathews. O'Callaghan made his debut in a friendly against Shelbourne