[1] Gilfillan went to school in Cradock, Eastern Cape, where his father Edward practised as a solicitor.
[1] During that time he joined the Barberton Scientific and Literary Society and met the plant collector Ernest Edward Galpin: this meeting initiated a life-long friendship between the two.
Sir Abe Bailey paid Gilfillan's fine and he was released and continued his legal practice.
[4][5] When the Boer War ended Gilfillan was appointed a member of the special criminal court for Johannesburg and acting magistrate for Boksburg and Germiston.
[1] These were collected in the areas around Johannesburg (1898- 1899), Middelburg, Eastern Cape (1899), Heidelberg, Gauteng and Witbank (1905).