Thomson represented New Zealand in cricket and hockey. In fact, he was part of the Black Caps hockey side in the 1968 Olympics. He usually played as a centre half or inside right. Interestingly, his hockey and cricket debut came against India. In 1961, he played his first hockey game for New Zealand at Lancaster Park.

Thomson was a middle-order batsman playing first class cricket for Canterbury. The reason behind him playing for New Zealand was in the 1966-67 Plunket Shield, he scored two hundreds. That allowed him to get a place in the Test side for the series against India in 1968. He scored 69 in his debut game and followed it with 25 and 0 in the next Test. Unfortunately, that was the last time he played for New Zealand.

After retiring from the game, Thomson kept himself involved in both cricket and hockey. He became an umpire in both the sports, officiating in 14 first class cricket games and two international hockey games that New Zealand played against Canada and India.