 In the 2008 Six Nations Championship, Barnes became the first English official ever to take charge of a match at Croke Park, in which Wales beat Ireland 16–12.In the 2009 Six Nations Championship, Barnes refereed the final-day decider between Wales and Ireland at the Millennium Stadium, Cardiff where Ireland were chasing their first Grand Slam for 61 years and Wales chasing the Championship.He was appointed in 2008 to take charge of his first Heineken Cup knockout match, between Stade Toulousain and Cardiff Blues at Le Stadium on 6 April 2008.