Hampden, March 21 against nine man Rangers. Nothing wrong with Mr Thomson's display that day from a St. Mirren perspective, but that's enough about that game. No point going into more detail about his history as the article for the final was fairly comprehensive - check it out here: http://www.stmirren-mad.co.uk/roll/ed16/know_the_ref__rangers_league_cup_final_507267/index.shtml
On the plus side, Mr Thomson's record with Kilmarnock this season is also rather poor. They have just one point to show for their four games, which came against Dundee United. Their other three games saw defeats to Hibs (who needed a penalty), Motherwell and Hamilton. Last season is even worse as they lost to the Accies again, as well as to Celtic in the league and the League Cup. The year before that is a bit better with goalless draws against Celtic and Hearts, despite finishing the Jambos game with just 10 men.
January 2006 yields another point, this time against Aberdeen, but you have to go back to 2002/03 for Mr Thomson's last Killie game before then. That season they lost to Dundee and Hearts, ending the latter with 10 men, but they did beat Livingston.
So, neither side has a great record with Mr Thomson in charge. Stick your money on a 0-0 on Saturday then!