Besides playing chess, he was also a writer, door-to-door salesman, journalist, and designer of crossword puzzles.

[1] Despite having so many different interests and activities to engage into, he nevertheless managed to succeed in chess to the point of becoming national champion in both of the countries he lived in.

He never became an International Master—he did eventually attain the required qualifications but declined to accept the award from FIDE.

He wrote several chess books, including Chess Springbok (1955), My Book of Fun and Games (1958), Grosse Remispartien (1968; in German; an English edition entitled Draw!, edited by John Nunn, was published in 1982), and Lacking the Master Touch (1970).

The Heidenfeld Trophy, the second division, of the Leinster chess league, is named in his honour.