A remarkably adept theoretician, Montgomery Judas Kielder achieved modest success in tournament play in his native South Africa before emigrating to the United States for a teaching position at Notre Dame. He never played competitively on American soil, but influenced a generation of young MC prodigies with his use of sophisticated mathematical analysis. His greatest theoretical contribution was of course his writings on the Kielder mapping, but he also added rigour to Fosdyke notation in the context of the modern game and lobbied the IMCS to regularise token weightings.
Kielder himself was the third youngest of eleven siblings, born into a disaffected Boer family which spent most of its time after the eponymous war trying to collect enough money to leave. His education was largely self-directed, consisting of long days spent in the mathematics section of any of a number of the Johannesburg libraries. He was nudged towards MC by a sympathetic librarian, but otherwise went his own way.
His Crescent playing career consisted largely of applying some of his own theories in a competitive context. He represented his University against a touring England team in 1947, and although he fared better than most inexperienced players would he later expressed regret that he did not compete sooner in order to strengthen his theoretical base.
He did play strongly enough in that tour and in other national competitions to attract the attention of the Notre Dame MCC, who were looking for outside talent to strengthen their team. He was employed at the University on condition (imposed by the INS) that he could not play competitively in the US. This irked him somewhat, but not enough to make him turn down the offer. In later years he said that stopping competitive play when he did was probably a good thing: he could concentrate on this analysis instead of diverting his energies into competition. Certainly, most of his best theoretical work was written after his move to the States.