Cockbain has not played for Wales in over a year after missing last season's RBS 6 Nations with a severe hamstring injury. He was then suspended for the autumn internationals. His brother is Matt Cockbain, the Australian World Cup winner. Cockbain played for Australia Under-19s and Under-21s before qualifying for Wales on residency. A lineout specialist, his Test debut came against Romania at Wrexham in 2003. Cockbain first played for London Irish and then Pontypridd, before joining the Celtic Warriors and then the Ospreys.