The former Republic of Ireland Under-21 internationalist started his career with Aston Villa as a youth before returning to his native Ireland, winning the FAI Cup in 2003 and 2004 and the League Cup in 2004 with Longford Town. He then moved to Shelbourne in 2006, collecting a league winner’s medal and scoring the winner in Shelbourne's 1-0 away win against FK Vetra in the Intertoto Cup.

In January 2007, Sean became Craig Levein's second major signing, when he penned a two year deal at Tannadice. After making his debut against Rangers at Ibrox, he missed the Scottish Cup tie with St Mirren as he joined United after the tournament transfer deadline. However he then went on to play in every match until the end of the season, appearing 16 times as he helped United climb away from the relegation zone.

Sean scored his first goal for the Club four games into the 2007-08 season, in a 3-0 win over Inverness CT, and by the end of February he had missed only one match due to suspension.

During that spell he also received international recognition when he played alongside then United team mate Noel Hunt for the Republic of Ireland B team in November 2007 in a match against a Scottish B team that included Darren Dods.

Injury and competition for places in Manager Craig Levein's growing squad of players meant that Sean would miss a further five games before the end of the season, but he was back in the team by April as United finished in the top six of the SPL.

Sean shared the right back slot with Mihael Kovacevic during the 2008-09 season, with both defenders playing approximately the same amount of matches throughout the season as United again just narrowly missed out on a European qualification place in the SPL.

The 2009-2010 season saw Sean used in a more versatile role than before, playing at left-back, centre-half and centre-midfield as well as his usual right-back position, and in November he made his 100th appearance in a tangerine jersey in United’s 2-0 victory over Kilmarnock at Rugby Park.

By the last third of the season, Sean was playing more regularly at left-back, taking over from the injured Paul Dixon, and it was in that role that he gave a solid performance in the Scottish Cup Final as United won the trophy for only the second time in the club’s history. United’s third place finish in the SPL will see Sean return to European football for the first time since his Shelbourne days.

Goals:

v Inverness CT (a) 3-0 25.08.07
v St Mirren (h) 1-1 27.02.08