His early education was in Gore, where his father was a labourer and then guard on the railway, before the family moved back to Invercargill. He excelled academically and was the top Southland student in the Public Service Examination in 1928 and top in Southland in Matriculation in 1929 with distinction in English, French and Latin. He was both Captain and Dux of the the school.
He won a scholarship to attend Sacred Heart College in Auckland in 1930, and from here won a University National Scholarship to attend University of Otago in 1931, studying English, French and Latin. In 1935 Davin won a Rhodes Scholarship to Oxford University and graduated with first-class honours in 1939.