Born on 18 March 1928 in Christchurch, Averill was educated at Christ's College, Christchurch, at Canterbury University College and then at the Otago Medical School. He spent two years as house surgeon to Palmerston North Hospital and then came to Britain to study ophthalmology at Moorfields, obtaining the DO in 1959 and his Fellowship in Ophthalmology in 1966. In 1967 he was appointed visiting ophthalmologist to Christchurch Hospital, having brought back from Britain a wealth of experience in new techniques for treating retinal detachment, and remained an expert in this field, being one of the first to use the laser for these operations. His leisure interests were in skiing, sailing, photography and amateur radio. He married Sheila Catlin in 1961, but she died in 1989. He was survived by three sons and a daughter. He died on 30 December 1994, aged 66 years.