Simpson played for the
Newcastle Knights at second-row forward in their
2001 NRL Grand Final victory over the
Parramatta Eels. Having won the
2001 NRL Premiership, the Knights travelled to England to play the
2002 World Club Challenge against
Super League champions, the
Bradford Bulls. Simpson played at second-row forward in Newcastle's loss. He was first selected to represent New South Wales as a second-rower for all three games of the
2002 State of Origin series. Simpson made his test debut in Australia's 64–10 victory over
Great Britain in July 2002. At the end of the
2003 NRL season, he went on the
2003 Kangaroo tour. Injuries prevented Simpson from being available for the 2003 and
2004 State of Origin series, he played in all games of the
2005,
2006 and
2007 series. He also participated in the 2006
ANZAC Tests against
New Zealand. Simpson was selected to play for the
Australian national team from the interchange bench in the 2007
ANZAC Test match victory against New Zealand. In August 2008, Simpson was named in the
preliminary 46-man Kangaroos squad for the
2008 Rugby League World Cup. He was selected for Country in the
City vs Country match on 8 May 2009. However, he did not play in the match after withdrawing with injury. He was offered to play for the
Ireland national rugby league team in the
2008 Rugby World Cup but declined. On 10 August 2010, Simpson announced his retirement after an ongoing knee injury did not respond well to treatment. In his career Simpson has played 216 games and scored 32 tries. ==References==