 Barnes refereed at the 2003 U19 World Cup in Saint-Denis, the 2005 Under 21 Rugby World Championship in Argentina, and was the English representative on the Sevens circuit from December 2003 to March 2005.In 2006, Barnes made his Test debut as a referee, taking charge of three matches in the inaugural Pacific Five Nations.Barnes was one of three English referees to officiate at the 2007 Rugby World Cup, the others being Chris White and Tony Spreadbury.