 During the 1958–59 season Prinsloo scored hat-tricks against Salford and Blackpool Borough for a season total of 27-tries from 31 games.Prinsloo played a vital part in finishing dazzling moves for many a St. Helens victory including the sensational 1959 Championship Final win by 44 points to 22 over a great Hunslet side where Prinsloo exhibited a fabulous touchline dash rounded off with his trademark 'swallow dive' over the tryline.During the 1959–60 season Prinsloo scored 4-tries against Liverpool City and a hat-trick of tries against Hull FC, finishing the season with 29-tries from 38 matches.