Tim, who began his rugby career with Ulster Rugby in the 2003-04 season, returned to Ulster Rugby at the start of the 2006-07 after a two year spell with Scottish club Glasgow.

He has represented Ireland at U21, U19 and U18 levels. During his first season back with Ulster Rugby Tim won 24 caps ensuring his reputation as a talented Lock.

Tim left Ulster Rugby in November 2007 in a move to Castres. Ulster Rugby Chief Executive Michael Reid said of Barker, "Tim has been a wonderful servant to Ulster Rugby and I have no doubt that his move to France will be a thoroughly enriching experience both in terms of his rugby career and the opportunity to immerse himself in a new way of life in an area steeped in rugby and he takes with him our very best wishes for his future"