Thompson reached the quarter-finals of the 2004 British Open, beating Tony David and Darryl Fitton before losing to Phill Nixon.
Thompson then won the unranked Welsh Classic, beating the Netherlands' Joey ten Berge in the final.
Thompson earned automatic qualification for the 2009 BDO World Championship, entering the tournament as the number 14 seed.
[1] Thompson was once again unseeded at the 2013 BDO World Championship, but this time won his first round match 3-1 over Gary Robson.
Thompson won the BDO British Open in 2013, arguably his biggest victory to date, beating James Wilson in the final.