After finishing his GCSEs, where he achieved three A grades, Primus signed a two-year apprenticeship with Charlton. He also received an offer from West Ham United, who were in a higher division, but he rejected this because he felt his first team opportunities would be greater at Charlton. Primus was playing in various positions until the club's youth team coach, Colin Clarke, decided that he should play as a centre back, "I see you as a centre back, that way you can see everything you want in front of you".