Born at Blackburn, Lancashire, on 4 September 1882, the eldest of the two sons and three daughters of George Ollerenshaw, JP, merchant, of Cherry Tree near Blackburn, and his wife Hannah Higginbottom. His father later lived at Glossop, Derbyshire. Ollerenshaw was educated at Manchester Grammar Schoo

Born on 18 January 1884 he was educated at Sydney Grammar School, matriculating in 1901. Early in his medical course he showed his interest in practical work and shared the Haswell Prize for practical biology, winning the John Harris scholarship in his third year. He was top in the fourth and fifth