 He earned a reputation as a hard-tackling defender whilst with the club, and formed the backbone of the team which won the League Championship in 1954–55, alongside the likes of Roy Bentley, Ken Armstrong, Eric Parsons and Derek Saunders, playing 39 games that season.Willemse also featured in the representative London XI side which reached the final of the 1955–58 Inter-Cities Fairs Cup.He only remained at Chelsea for one more season after that, and signed for Leyton Orient in 1956.