Eric Harrison was born at Clinkers Hill near Castlemaine in Victoria in 1886. Harrison left Australia for England in 1911 together with Harry Hawker, Harry Busteed and Harry Kauper all in search of careers in aviation. On his arrival in England Harrison trained as a pilot at the Bristol School and after a mere 30 minutes of actual flight time he attained his Aviator's Certificate from the Royal Aero Club. Soon after he was employed by Bristol as an instructor.
In December 1911, the Australian Defence Department advertised in England for "two competent mechanists and aviators" to establish a flying corps and school. Harry Busteed who was by now Bristol's chief test pilot, and Henry Petre ( a former solicitor) were selected. However, Harry Busteed withdrew his application which then paved the way for Eric Harrison, who was then commissioned in December 1912.