Whitridge was born on 14 August 1853 in Kensington, South Australia, the elder son of W. W. R. Whitridge (ca.1824–1861) and his wife Charlotte Elizabeth (ca.1821–1910). He was educated at Adelaide Educational Institution, and was already a keen cricketer, playing with distinction against rival school St. Peter's College. Whitridge was on the staff of the "South Australian Register" for 42 years, much of this time as head of the publishing department. His father and younger brother Fletcher were also with the "Register".