The American journalist George Thayer, who met with Tyndall in the 1960s, described him as being "blonde and balding", with "cold, evasive eyes". Thayer stated that Tyndall "had not the slightest spark of humour. He was suspicious, nervous, and excitable, and moved with all the stiffness of a Prussian in Court." In his study of the National Front, the journalist Martin Walker described Tyndall as giving off "an impression of absolute, if brittle, self control". Nigel Fielding, another to have studied the NF, described Tyndall as "a rather small man with a hard, unlined face and pale blue eyes. His movements are abrupt and energetic, and he speaks in a loud voice with a clipped inflection." Walker described him as having a "keen political mind", with a "concern for organisation meticulous planning". Tyndall lived a life of temperance and regular exercise, and—according to Walker—his early morning runs had "long been a joke in Nationalist circles".